Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2020-12-31 |
As at 2019-12-31 |
As at 2019-03-01 |
As at 2019-02-28 |
|---|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | ||||
| Property, plant and equipment [abstract] | ||||
| Property, plant and equipment |
167,890,000
EUR
|
181,616,000
EUR
|
172,866,000
EUR
|
— |
| Intangible assets and goodwill [abstract] | ||||
| Intangible assets and goodwill |
4,468,000
EUR
|
22,096,000
EUR
|
21,309,000
EUR
|
— |
| Trade and other non-current receivables [abstract] | ||||
| Non-current receivables due from related parties |
5,416,000
EUR
|
5,633,000
EUR
|
6,156,000
EUR
|
— |
| Other non-current receivables |
9,405,000
EUR
|
8,838,000
EUR
|
8,657,000
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 |
3,021,000
EUR
|
5,433,000
EUR
|
15,099,000
EUR
|
— |
| Miscellaneous non-current assets [abstract] | ||||
| Non-current derivative financial assets |
2,109,000
EUR
|
0
EUR
|
0
EUR
|
— |
| Trade and other current receivables [abstract] | ||||
| Current trade receivables |
61,374,000
EUR
|
98,824,000
EUR
|
95,998,000
EUR
|
— |
| Current receivables due from related parties |
18,610,000
EUR
|
19,390,000
EUR
|
24,218,000
EUR
|
— |
| Other current receivables |
24,376,000
EUR
|
35,125,000
EUR
|
37,949,000
EUR
|
— |
| Classes of current inventories [abstract] | ||||
| Current inventories |
105,571,000
EUR
|
122,798,000
EUR
|
123,781,000
EUR
|
— |
| Classes of current inventories, alternative [abstract] | ||||
| Cash and cash equivalents [abstract] | ||||
| Cash and cash equivalents |
92,548,000
EUR
|
75,790,000
EUR
|
90,062,000
EUR
|
90,062,000
EUR
|
| Miscellaneous current assets [abstract] | ||||
| Current derivative financial assets |
14,362,000
EUR
|
0
EUR
|
0
EUR
|
— |
| Classes of other provisions [abstract] | ||||
| Other provisions [abstract] | ||||
| Other non-current provisions |
0
EUR
|
0
EUR
|
12,000
EUR
|
— |
| Non-current portion of non-current borrowings, by type [abstract] | ||||
| Non-current portion of non-current bonds issued |
0
EUR
|
0
EUR
|
89,769,000
EUR
|
— |
| Non-current portion of non-current notes and debentures issued |
70,000,000
EUR
|
70,000,000
EUR
|
0
EUR
|
— |
| Non-current portion of other non-current borrowings |
13,209,000
EUR
|
18,718,000
EUR
|
32,464,000
EUR
|
— |
| Current borrowings and current portion of non-current borrowings, by type [abstract] | ||||
| Current bonds issued and current portion of non-current bonds issued |
0
EUR
|
89,916,000
EUR
|
0
EUR
|
— |
| Current notes and debentures issued and current portion of non-current notes and debentures issued |
0
EUR
|
0
EUR
|
34,000,000
EUR
|
— |
| Other current borrowings and current portion of other non-current borrowings |
159,219,000
EUR
|
25,994,000
EUR
|
69,021,000
EUR
|
— |
| Trade and other non-current payables [abstract] | ||||
| 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 deferred income other than non-current contract liabilities | — | — | — | — |
| Non-current government grants |
9,125,000
EUR
|
8,385,000
EUR
|
9,866,000
EUR
|
— |
| Other non-current payables |
63,000
EUR
|
66,000
EUR
|
22,000
EUR
|
— |
| Trade and other current payables [abstract] | ||||
| Current trade payables |
26,956,000
EUR
|
83,465,000
EUR
|
74,819,000
EUR
|
— |
| Current payables to related parties |
8,479,000
EUR
|
4,508,000
EUR
|
4,623,000
EUR
|
— |
| 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 |
6,026,000
EUR
|
4,845,000
EUR
|
17,312,000
EUR
|
— |
| Current deferred income other than current contract liabilities | — | — | — | — |
| Current government grants |
858,000
EUR
|
1,327,000
EUR
|
946,000
EUR
|
— |
| Other current payables |
17,734,000
EUR
|
18,994,000
EUR
|
21,417,000
EUR
|
— |
| Miscellaneous non-current liabilities [abstract] | ||||
| Non-current derivative financial liabilities |
0
EUR
|
14,000
EUR
|
64,000
EUR
|
— |
| Miscellaneous current liabilities [abstract] | ||||
| Current derivative financial liabilities |
0
EUR
|
1,910,000
EUR
|
10,532,000
EUR
|
— |
| Issued capital [abstract] | ||||
| Issued capital |
45,790,000
EUR
|
45,790,000
EUR
|
45,790,000
EUR
|
— |
| Retained earnings [abstract] | ||||
| Retained earnings |
28,757,000
EUR
|
48,332,000
EUR
|
44,063,000
EUR
|
— |
| Accumulated other comprehensive income [abstract] | ||||
| Reserve of exchange differences on translation |
954,000
EUR
|
621,000
EUR
|
665,000
EUR
|
— |
| Miscellaneous equity [abstract] | ||||
| Additional paid-in capital |
221,459,000
EUR
|
221,459,000
EUR
|
221,459,000
EUR
|
— |
| Net assets (liabilities) [abstract] | ||||
| Assets |
649,522,000
EUR
|
736,740,000
EUR
|
766,883,000
EUR
|
— |
| Net current assets (liabilities) [abstract] | ||||
| Current assets |
322,670,000
EUR
|
361,049,000
EUR
|
387,237,000
EUR
|
— |
| Current liabilities |
226,735,000
EUR
|
237,670,000
EUR
|
246,886,000
EUR
|
— |
| Assets less current liabilities [abstract] |