Stock-based Compensation Plans - Additional Information 3 (Detail) - USD ($) $ in Thousands, shares in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Maximum percentage of employees contribution									75.00%
Maximum percentage of employers contribution in cash									6.00%
Employer contribution									$ 6,100	$ 5,800
Deferred compensation plan vesting period									3 years
Deferred compensation plan	$ (21,016)	$ (43,705)	$ (7,282)	$ (5,624)	$ (36,836)	$ (46,198)	$ 10,519	$ (2,035)	$ (77,627)	$ (74,550)	$ 55,296
Shares held in rabbi trust total	2.8				2.8				2.8	2.8
Vested shares held in rabbi trust	2.5				2.5				2.5	2.5