Stock-Based Compensation Plans - Additional Information 3 (Detail) - USD ($) $ in Thousands, shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Deferred compensation plan vesting period			3 years
Deferred compensation plan	$ (11,636)	$ (43,705)	$ 30,166	$ (56,611)
Shares held in rabbi trust total	2.8		2.8		2.8
Vested shares held in rabbi trust	2.3		2.3		2.5