Deferred Compensation - Additional Information (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Deferred compensation	[1]	$ 6,500,000	$ (11,903,000)	$ 9,496,000
Deferred compensation liability		$ 43,988,000	$ 38,730,000

[1] In 2014 and 2013, deferred compensation expense (income) was included in administrative expenses. The 2014 and 2013 amounts have been changed to conform to the current year presentation.