Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2018-12-31 |
As at 2018-12-31 |
|---|---|---|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | ||||||
| Property, plant and equipment [abstract] | ||||||
| Property, plant and equipment |
664,644,000
EUR
|
600,532,000
EUR
|
584,117,000
EUR
|
656,383,000
EUR
|
— | — |
| Intangible assets and goodwill [abstract] | ||||||
| Intangible assets and goodwill |
190,033,000
EUR
|
141,451,000
EUR
|
132,692,000
EUR
|
194,945,000
EUR
|
— | — |
| Investment property [abstract] | ||||||
| Investment property |
1,258,000
EUR
|
4,230,000
EUR
|
4,002,000
EUR
|
1,030,000
EUR
|
— | — |
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements [abstract] | ||||||
| Investments in subsidiaries reported in separate financial statements |
0
EUR
|
37,001,000
EUR
|
37,001,000
EUR
|
0
EUR
|
— | — |
| Trade and other non-current receivables [abstract] | ||||||
| Trade and other non-current receivables |
17,081,000
EUR
|
17,081,000
EUR
|
24,405,000
EUR
|
24,405,000
EUR
|
— | — |
| Non-current prepayments and non-current accrued income including non-current contract assets [abstract] | ||||||
| Non-current accrued income including non-current contract assets [abstract] | ||||||
| Non-current contract assets |
2,668,000
EUR
|
2,337,000
EUR
|
3,280,000
EUR
|
3,646,000
EUR
|
— | — |
| Miscellaneous non-current assets [abstract] | ||||||
| Non-current investments other than investments accounted for using equity method |
3,068,000
EUR
|
63,951,000
EUR
|
90,421,000
EUR
|
4,860,000
EUR
|
— | — |
| Trade and other current receivables [abstract] | ||||||
| Trade and other current receivables |
162,936,000
EUR
|
158,367,000
EUR
|
145,644,000
EUR
|
153,559,000
EUR
|
— | — |
| Current prepayments and current accrued income including current contract assets [abstract] | ||||||
| Current accrued income including current contract assets [abstract] | ||||||
| Current contract assets |
23,527,000
EUR
|
23,309,000
EUR
|
22,813,000
EUR
|
22,780,000
EUR
|
— | — |
| Classes of current inventories [abstract] | ||||||
| Current inventories |
26,175,000
EUR
|
21,811,000
EUR
|
20,579,000
EUR
|
24,620,000
EUR
|
— | — |
| Classes of current inventories, alternative [abstract] | ||||||
| Cash and cash equivalents [abstract] | ||||||
| Cash and cash equivalents |
8,167,000
EUR
|
2,086,000
EUR
|
1,153,000
EUR
|
13,219,000
EUR
|
10,684,000
EUR
|
2,011,000
EUR
|
| Non-current assets or disposal groups classified as held for sale or as held for distribution to owners [abstract] | ||||||
| Non-current assets or disposal groups classified as held for sale |
214,000
EUR
|
214,000
EUR
|
500,000
EUR
|
500,000
EUR
|
— | — |
| Miscellaneous current assets [abstract] | ||||||
| Current investments |
512,000
EUR
|
17,385,000
EUR
|
10,226,000
EUR
|
679,000
EUR
|
— | — |
| Borrowings [abstract] | ||||||
| Non-current portion of non-current borrowings |
184,221,000
EUR
|
184,221,000
EUR
|
214,802,000
EUR
|
214,802,000
EUR
|
— | — |
| Current borrowings and current portion of non-current borrowings [abstract] | ||||||
| Current borrowings and current portion of non-current borrowings |
32,080,000
EUR
|
45,083,000
EUR
|
38,008,000
EUR
|
31,038,000
EUR
|
— | — |
| Non-current portion of non-current borrowings, by type [abstract] | ||||||
| Current borrowings and current portion of non-current borrowings, by type [abstract] | ||||||
| Trade and other non-current payables [abstract] | ||||||
| Non-current payables for purchase of non-current assets |
38,896,000
EUR
|
20,856,000
EUR
|
10,722,000
EUR
|
40,469,000
EUR
|
— | — |
| Non-current accruals and non-current deferred income including non-current contract liabilities [abstract] | ||||||
| Non-current deferred income including non-current contract liabilities [abstract] | ||||||
| Non-current contract liabilities [abstract] | ||||||
| Non-current contract liabilities |
15,772,000
EUR
|
14,974,000
EUR
|
15,655,000
EUR
|
16,691,000
EUR
|
— | — |
| Trade and other current payables [abstract] | ||||||
| Current accruals and current deferred income including current contract liabilities [abstract] | ||||||
| Current deferred income including current contract liabilities [abstract] | ||||||
| Current contract liabilities [abstract] | ||||||
| Current contract liabilities |
12,721,000
EUR
|
8,869,000
EUR
|
5,412,000
EUR
|
9,103,000
EUR
|
— | — |
| Accruals classified as current |
41,792,000
EUR
|
40,371,000
EUR
|
35,273,000
EUR
|
37,936,000
EUR
|
— | — |
| Trade and other current payables |
119,058,000
EUR
|
109,755,000
EUR
|
99,945,000
EUR
|
113,342,000
EUR
|
— | — |
| Issued capital [abstract] | ||||||
| Issued capital |
272,721,000
EUR
|
272,721,000
EUR
|
272,721,000
EUR
|
272,721,000
EUR
|
— | — |
| Retained earnings [abstract] | ||||||
| Retained earnings |
33,305,000
EUR
|
50,359,000
EUR
|
48,886,000
EUR
|
31,589,000
EUR
|
— | — |
| Accumulated other comprehensive income [abstract] | ||||||
| Reserve of exchange differences on translation |
25,000
EUR
|
0
EUR
|
0
EUR
|
6,000
EUR
|
— | — |
| Reserve of remeasurements of defined benefit plans |
2,988,000
EUR
|
2,733,000
EUR
|
2,069,000
EUR
|
2,347,000
EUR
|
— | — |
| Miscellaneous equity [abstract] | ||||||
| Statutory reserve |
54,854,000
EUR
|
54,544,000
EUR
|
54,544,000
EUR
|
54,854,000
EUR
|
— | — |
| Capital reserve |
181,489,000
EUR
|
180,956,000
EUR
|
180,956,000
EUR
|
181,488,000
EUR
|
— | — |
| Net assets (liabilities) [abstract] | ||||||
| Assets |
1,227,839,000
EUR
|
1,226,566,000
EUR
|
1,223,536,000
EUR
|
1,250,211,000
EUR
|
— | — |
| Liabilities |
637,355,000
EUR
|
620,782,000
EUR
|
617,400,000
EUR
|
659,623,000
EUR
|
— | — |
| Net current assets (liabilities) [abstract] | ||||||
| Current assets |
225,781,000
EUR
|
227,912,000
EUR
|
216,424,000
EUR
|
233,995,000
EUR
|
— | — |
| Current liabilities |
317,160,000
EUR
|
316,975,000
EUR
|
189,850,000
EUR
|
201,983,000
EUR
|
— | — |
| Assets less current liabilities [abstract] |