Stock-based Compensation Plans - Additional Information 3 (Detail) - USD ($) $ in Thousands, shares in Millions |
3 Months Ended | ||
|---|---|---|---|
Mar. 31, 2017 |
Mar. 31, 2016 |
Dec. 31, 2016 |
|
| Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] | |||
| Deferred compensation plan vesting period | 3 years | ||
| Deferred compensation plan | $ (13,169) | $ 16,056 | |
| Shares held in rabbi trust total | 2.7 | 2.7 | |
| Vested shares held in rabbi trust | 2.2 | 2.3 | |