Stock-Based Compensation Plans - Summary of Stock Option Award Activity (Detail) - Stock Options |
3 Months Ended |
|---|---|
|
Mar. 31, 2018
$ / shares
shares
| |
| Number of Shares | |
| Outstanding, beginning balance | shares | 8,465,398 |
| Granted | shares | 529,197 |
| Exercised | shares | (477,086) |
| Forfeited or expired | shares | (4,512) |
| Outstanding, ending balance | shares | 8,512,997 |
| Weighted Average Exercise Price | |
| Outstanding, beginning balance (in USD per share) | $ / shares | $ 33.74 |
| Granted (in USD per share) | $ / shares | 64.79 |
| Exercised (in USD per share) | $ / shares | 24.68 |
| Forfeited or expired (in USD per share) | $ / shares | 49.94 |
| Outstanding, ending balance (in USD per share) | $ / shares | $ 36.17 |