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Share-Based Compensation - Summary of Movements in Shares (Detail) | 6 Months Ended
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Jun. 30, 2018 shares
Disclosure of movement of potential shares [line items] |
Potential Shares, Beginning balance | 4,297,680
Potential Shares, Granted | 1,319,604
Potential Shares, Over performance | 295,517
Potential Shares, Vested | (182,716)
Potential Shares, Forfeited | (161,222)
Potential Shares, Ending balance | 5,568,863
Performance-Based RSU [member] |
Disclosure of movement of potential shares [line items] |
Potential Shares, Beginning balance | 3,257,840
Potential Shares, Granted | 701,109
Potential Shares, Over performance | 295,517
Potential Shares, Vested | (34,580)
Potential Shares, Forfeited | (134,163)
Potential Shares, Ending balance | 4,085,723
Restricted Stock Units [member] |
Disclosure of movement of potential shares [line items] |
Potential Shares, Beginning balance | 944,500
Potential Shares, Granted | 587,786
Potential Shares, Vested | (80,000)
Potential Shares, Forfeited | (27,059)
Potential Shares, Ending balance | 1,425,227
Equity Awards Plans [member] |
Disclosure of movement of potential shares [line items] |
Potential Shares, Beginning balance | 95,340
Potential Shares, Granted | 30,709
Potential Shares, Vested | (68,136)
Potential Shares, Ending balance | 57,913

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