Financial risk management - Additional Information (Details) £ in Millions | 12 Months Ended | | | | | |
Dec. 31, 2018EUR (€) | Dec. 31, 2018USD ($) | Dec. 31, 2017EUR (€) | Dec. 31, 2016EUR (€) | Dec. 31, 2018USD ($) | Dec. 31, 2018GBP (£) | Jun. 15, 2018EUR (€) | Jun. 15, 2018USD ($) | Dec. 31, 2017USD ($) | Dec. 31, 2017GBP (£) | Dec. 20, 2017EUR (€) | Dec. 20, 2017USD ($) | May 03, 2017EUR (€) | May 03, 2017USD ($) |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Financial Assets (Financial Liabilities) At Fair Value Through Other Comprehensive Income | € 7,900,000 | | € (51,000,000) | | | | | | | | | | | |
Financial Assets (Liabilities), Net | (1,872,000,000) | | (1,585,700,000) | | | | | | | | | | | |
Financial liabilities at amortised cost | 2,310,100,000 | | 1,851,100,000 | | | | | | | | | | | |
Financial assets at fair value through profit or loss | 30,600,000 | | | | | | | | | | | | | |
Gross amount of financial instruments as presented upon balance sheet | 49,100,000 | | 20,700,000 | | | | | | | | | | | |
Gross financial liabilities set off against financial assets subject to offsetting, enforceable master netting arrangements or similar agreements | 29,800,000 | | 20,700,000 | | | | | | | | | | | |
Gains (losses) on hedges of net investments in foreign operations, net of tax | 3,400,000 | | 8,100,000 | € 35,400,000 | | | | | | | | | | |
Gain (loss) on hedge ineffectiveness | € 300,000 | | | | | | | | | | | | | |
Cross currency interest rate swap where hedge accounting not applied | 14.70% | 14.70% | | | | | | | | | | | | |
Financial assets at amortised cost | € 395,300,000 | | | | | | | | | | | | | |
Net financial assets subject to offsetting, enforceable master netting arrangements or similar agreements in statement of financial position | 19,300,000 | | 0 | | | | | | | | | | | |
Gross financial liabilities subject to offsetting, enforceable master netting arrangements or similar agreements | 36,900,000 | | 69,200,000 | | | | | | | | | | | |
Related financial instruments that are offset | 29,800,000 | | 20,700,000 | | | | | | | | | | | |
Net financial liabilities subject to offsetting, enforceable master netting arrangements or similar agreements in statement of financial position | 7,100,000 | | 48,500,000 | | | | | | | | | | | |
Derivatives at fair value through profit or loss | € 4,300,000 | | | | | | | | | | | | | |
Interest rate risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent | 1.00% | 1.00% | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, impact on pre-tax earnings | € 5,700,000 | | € 5,100,000 | | | | | | | | | | | |
Liquidity risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Line of credit facility, maximum borrowing capacity | € 80,000,000 | | | | | | | | | | | | | |
Letters of credit, overdrafts, customer bonds and bank guarantees utilized against the credit facility | $ | | | | | $ 16,800,000 | | | | | | | | | |
Pound Sterling | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, actual change in risk variable, percent | 1.30% | 1.30% | 3.90% | | | | | | | | | | | |
US dollar | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, actual change in risk variable, percent | 4.50% | 4.50% | 13.90% | | | | | | | | | | | |
Swedish Krona | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, actual change in risk variable, percent | 4.10% | 4.10% | 2.70% | | | | | | | | | | | |
Interest rate swap contract [member] | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, impact on interest charge | € 500,000 | | | | | | | | | | | | | |
Interest rate swap contract [member] | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, impact on interest charge | € 2,500,000 | | € 2,200,000 | | | | | | | | | | | |
Cross currency interest rate swap | Pound Sterling | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent | 1.00% | 1.00% | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, impact on interest charge | € 100,000 | | 100,000 | | | | | | | | | | | |
Foreign exchange forward contract | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Gains (losses) on change in fair value of derivatives | € 0 | | 0 | € 1,000,000 | | | | | | | | | | |
Foreign exchange forward contract | Pound Sterling | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent | 1.00% | 1.00% | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, impact on pre-tax earnings | € 1,200,000 | | 700,000 | | | | | | | | | | | |
Foreign exchange forward contract | US dollar | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent | 1.00% | 1.00% | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, impact on pre-tax earnings | € 2,300,000 | | 2,400,000 | | | | | | | | | | | |
Foreign exchange forward contract | Swedish Krona | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent | 1.00% | 1.00% | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, impact on pre-tax earnings | € 1,300,000 | | € 700,000 | | | | | | | | | | | |
Derivative financial instruments | Cross currency interest rate swap | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Notional amount | € 312,900,000 | | | | | | | | | | | | | |
Derivative financial instruments | Foreign exchange forward contract | US dollar | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Percentage of financial instruments designated as hedging instruments | 85.20% | | 70.00% | | 85.20% | 85.20% | | | 70.00% | 70.00% | | | | |
Financial asset | € 10,600,000 | | € 6,500,000 | | | | | | | | | | | |
Derivative financial instruments | Foreign exchange forward contract | Euro | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Percentage of financial instruments designated as hedging instruments | 70.00% | | 68.00% | | 70.00% | 70.00% | | | 68.00% | 68.00% | | | | |
Financial asset | € 1,100,000 | | € 1,500,000 | | | | | | | | | | | |
Cross currency interest rate swap | Pound Sterling | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent | | | 1.00% | 1.00% | | | | | | | | | | |
Hedges of net investment in foreign operations [member] | Cross currency interest rate swap | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Gain (loss) on hedge ineffectiveness | | | € 0 | | | | | | | | | | | |
Hedges of net investment in foreign operations [member] | Cross currency interest rate swap | Pound Sterling | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Percentage of financial instruments designated as hedging instruments | 85.30% | | 82.80% | | 85.30% | 85.30% | | | 82.80% | 82.80% | | | | |
Hedges of net investment in foreign operations [member] | Cross currency interest rate swap | Pound Sterling | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Risk exposure associated with instruments sharing characteristic, concentration percentage | | | 93.00% | | | | | | 93.00% | 93.00% | | | | |
Gains (losses) on hedges of net investments in foreign operations, net of tax | € 3,400,000 | | | | | | | | | | | | | |
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent | 1.00% | 1.00% | | | | | | | | | | | | |
Hedges of net investment in foreign operations [member] | Loans and Borrowings | Pound Sterling | Currency risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Risk exposure associated with instruments sharing characteristic, concentration percentage | 103.00% | | | | 103.00% | 103.00% | | | | | | | | |
Gain on retranslation of loans | | | € 12,400,000 | | | | | | | | | | | |
Hedges of net investment in foreign operations [member] | Derivative financial instruments | Cross currency interest rate swap | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Carrying amount of cross currency interest rate swaps | € 21,600,000 | | € 15,300,000 | | | | | | | | | | | |
Notional amount | £ | | | | | | £ 224.7 | | | | | | | | |
maturity date | May 15, 2022 | May 15, 2022 | May 15, 2022 | | | | | | | | | | | |
Change in fair value of outstanding hedging instruments | € 3,700,000 | | € 12,400,000 | | | | | | | | | | | |
Change in value of hedged item | € (3,400,000) | | € (12,400,000) | | | | | | | | | | | |
Average rate of hedging instrument | 119.00% | | 120.00% | | 119.00% | 119.00% | | | 120.00% | 120.00% | | | | |
Cash flow hedges [member] | Foreign Exchange Forward And Currency Swap Contract [Member] | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Gains (losses) on change in fair value of derivatives | € 1,000,000 | | € 3,500,000 | € 4,300,000 | | | | | | | | | | |
Cash flow hedges [member] | Derivative financial instruments | Cross currency interest rate swap | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Carrying amount of cross currency interest rate swaps | (25,600,000) | | € (61,300,000) | | | | | | | | | | | |
Notional amount | € 0 | | | | | £ 263.4 | | | | | | | | |
maturity date | May 15, 2022 | May 15, 2022 | May 15, 2022 | | | | | | | | | | | |
Change in fair value of outstanding hedging instruments | € 35,600,000 | | € (61,300,000) | | | | | | | | | | | |
Change in value of hedged item | € (35,600,000) | | € 61,300,000 | | | | | | | | | | | |
Average rate of hedging instrument | 111.00% | | 107.00% | | 111.00% | 111.00% | | | 107.00% | 107.00% | | | | |
Currency swap contract [member] | Foreign Exchange Forward And Currency Swap Contract [Member] | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Gains (losses) on change in fair value of derivatives | € 400,000 | | € 3,900,000 | € 0 | | | | | | | | | | |
Senior USD Debt [Member] | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Notional amount | $ | | | | | $ 953,400,000 | | | $ 953,400,000 | $ 610,000,000 | | | $ 610,000,000 | | $ 610,000,000 |
Increase in debt | $ | | $ 343,400,000 | | | | | | | | | | | | |
Pound Sterling | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Notional amount | £ | | | | | | £ 224.7 | | | | £ 187.6 | | | | |
2024 fixed rate senior secured notes | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Notional amount | | | | | | | | | | | | | € 400,000,000 | |
Interest rate | | | | | | | | | | | | | 3.25% | 3.25% |
Senior EURO Debt | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Notional amount | | | | | | | € 558,000,000 | | | | € 500,000,000 | | € 500,000,000 | |
Bottom of range | Interest rate risk | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Interest rate | 0.00% | | | | 0.00% | 0.00% | | | | | | | | |
EUR/USD [Domain] | Foreign exchange forward contract | Derivative financial instruments | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Carrying amount of cross currency interest rate swaps | € 8,400,000 | | (5,000,000) | | | | | | | | | | | |
Notional amount | 224,900,000 | | 134,500,000 | | | | | | | | | | | |
Change in fair value of outstanding hedging instruments | € 14,100,000 | | € (15,600,000) | | | | | | | | | | | |
Average rate of hedging instrument | 120.00% | | 116.00% | | 120.00% | 120.00% | | | 116.00% | 116.00% | | | | |
GBP/USD [Domain] [Domain] | Foreign exchange forward contract | Derivative financial instruments | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Carrying amount of cross currency interest rate swaps | € 2,000,000 | | € (1,500,000) | | | | | | | | | | | |
Notional amount | 47,200,000 | | 52,300,000 | | | | | | | | | | | |
Change in fair value of outstanding hedging instruments | € 4,500,000 | | € (3,700,000) | | | | | | | | | | | |
Average rate of hedging instrument | 134.00% | | 132.00% | | 134.00% | 134.00% | | | 132.00% | 132.00% | | | | |
GBP/EUR [Domain] | Foreign exchange forward contract | Derivative financial instruments | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Carrying amount of cross currency interest rate swaps | € 1,400,000 | | € (100,000) | | | | | | | | | | | |
Notional amount | 97,400,000 | | 46,300,000 | | | | | | | | | | | |
Change in fair value of outstanding hedging instruments | € 1,900,000 | | € (3,900,000) | | | | | | | | | | | |
Average rate of hedging instrument | 112.00% | | 112.00% | | 112.00% | 112.00% | | | 112.00% | 112.00% | | | | |
SEKEUR [Domain] | Foreign exchange forward contract | Derivative financial instruments | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Carrying amount of cross currency interest rate swaps | € (600,000) | | € 1,300,000 | | | | | | | | | | | |
Notional amount | 65,600,000 | | 65,900,000 | | | | | | | | | | | |
Change in fair value of outstanding hedging instruments | € 1,500,000 | | € 2,600,000 | | | | | | | | | | | |
Average rate of hedging instrument | 10.00% | | 10.00% | | 10.00% | 10.00% | | | 10.00% | 10.00% | | | | |
Other currencies [Domain] | Foreign exchange forward contract | Derivative financial instruments | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Carrying amount of cross currency interest rate swaps | € 500,000 | | € 300,000 | | | | | | | | | | | |
Notional amount | 38,500,000 | | 29,800,000 | | | | | | | | | | | |
Change in fair value of outstanding hedging instruments | € 800,000 | | € (200,000) | | | | | | | | | | | |
Average rate of hedging instrument | 0.00% | | 0.00% | | 0.00% | 0.00% | | | 0.00% | 0.00% | | | | |
Cash and cash equivalents | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Financial assets at fair value through profit or loss | € 30,600,000 | | € 0 | | | | | | | | | | | |
Financial asset | 327,600,000 | | 219,200,000 | | | | | | | | | | | |
Financial assets at fair value through other comprehensive income | 0 | | 0 | | | | | | | | | | | |
Financial assets at amortised cost | 297,000,000 | | | | | | | | | | | | | |
Derivatives at fair value through profit or loss | 0 | | | | | | | | | | | | | |
Trade receivables | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Financial assets at fair value through profit or loss | 0 | | 0 | | | | | | | | | | | |
Financial asset | 98,300,000 | | 94,700,000 | | | | | | | | | | | |
Financial assets at fair value through other comprehensive income | 0 | | 0 | | | | | | | | | | | |
Financial assets at amortised cost | 98,300,000 | | | | | | | | | | | | | |
Derivatives at fair value through profit or loss | 0 | | | | | | | | | | | | | |
Derivative financial instruments | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Financial assets at fair value through profit or loss | 0 | | 3,200,000 | | | | | | | | | | | |
Financial asset | 49,100,000 | | 20,700,000 | | | | | | | | | | | |
Financial assets at fair value through other comprehensive income | 44,500,000 | | 17,500,000 | | | | | | | | | | | |
Financial assets at amortised cost | 0 | | | | | | | | | | | | | |
Derivatives at fair value through profit or loss | 4,600,000 | | | | | | | | | | | | | |
Loans and Borrowings Excluding Deferred Borrowing Costs [Member] | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Financial liabilities at amortised cost | 1,775,200,000 | | 1,409,500,000 | | | | | | | | | | | |
Financial liabilities | 1,775,200,000 | | 1,409,500,000 | | | | | | | | | | | |
Financial Liabilities At Fair Value Through Other Comprehensive Income | 0 | | 0 | | | | | | | | | | | |
Financial assets at fair value through profit or loss | 0 | | | | | | | | | | | | | |
Financial assets at amortised cost | 0 | | | | | | | | | | | | | |
Derivatives at fair value through profit or loss | 0 | | | | | | | | | | | | | |
Trade and other payables excluding non-financial liabilities | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Financial liabilities at amortised cost | 534,900,000 | | 441,600,000 | | | | | | | | | | | |
Financial liabilities | 534,900,000 | | 441,600,000 | | | | | | | | | | | |
Financial Liabilities At Fair Value Through Other Comprehensive Income | 0 | | 0 | | | | | | | | | | | |
Financial assets at fair value through profit or loss | 0 | | | | | | | | | | | | | |
Financial assets at amortised cost | 0 | | | | | | | | | | | | | |
Derivatives at fair value through profit or loss | 0 | | | | | | | | | | | | | |
Derivative financial instruments | | | | | | | | | | | | | | |
Disclosure of nature and extent of risks arising from financial instruments [line items] | | | | | | | | | | | | | | |
Financial liabilities at amortised cost | 0 | | 0 | | | | | | | | | | | |
Financial liabilities | 36,900,000 | | 69,200,000 | | | | | | | | | | | |
Financial Liabilities At Fair Value Through Other Comprehensive Income | 36,600,000 | | € 68,500,000 | | | | | | | | | | | |
Financial assets at fair value through profit or loss | 0 | | | | | | | | | | | | | |
Financial assets at amortised cost | 0 | | | | | | | | | | | | | |
Derivatives at fair value through profit or loss | € 300,000 | | | | | | | | | | | | | |