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Shareholders' Equity - Schedule of Share Capital Transactions Relating To Common Shares A (Detail) - Common Share [member] - shares
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Summary of issued share capital and reserves attributable to shareholders [line items]      
Issuance of common shares with a par value of EUR 0.12     21,099
Final dividend [member]      
Summary of issued share capital and reserves attributable to shareholders [line items]      
Dividend (32,874,000) (21,954,000) (26,916,000)
Share buyback program 32,874,000 21,954,000 51,865,000
Interim dividend [member]      
Summary of issued share capital and reserves attributable to shareholders [line items]      
Dividend (35,370,000) (24,134,000) (24,948,000)
Share buyback program 43,150,000 24,134,000 51,865,000