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v3.19.1

Share-Based Compensation - Summary of Movements in Shares (Detail) | 12 Months Ended
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Dec. 31, 2018 EUR (€) shares | Dec. 31, 2017 EUR (€) shares
Performance-Based RSU [member] |  |
Disclosure of movement of potential shares [line items] |  |
Potential Shares, Beginning balance | shares | 3,257,840 | 2,066,835
Potential Shares, Granted | shares | 701,109 | 892,781
Potential Shares, Over performance | shares | 633,670 | 552,728
Potential Shares, Vested | shares | (1,265,635) |
Potential Shares, Forfeited | shares | (241,820) | (254,504)
Potential Shares, Ending balance | shares | 3,085,164 | 3,257,840
Weighted- Average Grant-Date Fair Value per Share, Beginning balance | € | € 8.56 | € 7.50
Weighted- Average Grant-Date Fair Value per Share, Granted | € | 15.31 | 11.52
Weighted- Average Grant-Date Fair Value per Share, Over performance | € | 7.28 | 7.63
Weighted- Average Grant-Date Fair Value per Share, Vested | € | 7.09 |
Weighted- Average Grant-Date Fair Value per Share, Forfeited | € | 8.40 | 8.29
Weighted- Average Grant-Date Fair Value per Share, Ending balance | € | € 10.45 | € 8.56
Restricted Stock Units [member] |  |
Disclosure of movement of potential shares [line items] |  |
Potential Shares, Beginning balance | shares | 944,500 | 479,500
Potential Shares, Granted | shares | 595,687 | 703,180
Potential Shares, Vested | shares | (155,000) | (125,000)
Potential Shares, Forfeited | shares | (72,663) | (113,180)
Potential Shares, Ending balance | shares | 1,312,524 | 944,500
Weighted- Average Grant-Date Fair Value per Share, Beginning balance | € | € 7.76 | € 7.82
Weighted- Average Grant-Date Fair Value per Share, Granted | € | 10.23 | 7.50
Weighted- Average Grant-Date Fair Value per Share, Vested | € | 10.83 | 7.02
Weighted- Average Grant-Date Fair Value per Share, Forfeited | € | 8.57 | 7.27
Weighted- Average Grant-Date Fair Value per Share, Ending balance | € | € 8.47 | € 7.76
Equity Awards Plans [member] |  |
Disclosure of movement of potential shares [line items] |  |
Potential Shares, Beginning balance | shares | 95,340 | 94,881
Potential Shares, Granted | shares | 30,709 | 54,409
Potential Shares, Vested | shares | (68,136) | (53,950)
Potential Shares, Ending balance | shares | 57,913 | 95,340
Weighted- Average Grant-Date Fair Value per Share, Beginning balance | € | € 5.20 | € 5.01
Weighted- Average Grant-Date Fair Value per Share, Granted | € | 10.27 | 6.09
Weighted- Average Grant-Date Fair Value per Share, Vested | € | 4.85 | 5.76
Weighted- Average Grant-Date Fair Value per Share, Ending balance | € | € 8.31 | € 5.20

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