Summary of Components of Long-Term Debt Obligations (Detail) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Total debt		$ 370,000	$ 500,000
Less deferred debt issue costs		(4,472)	(5,228)
Long-term debt, net	[1]	365,528	494,772
Senior Bank Credit Facility
Debt Instrument [Line Items]
Credit facility		70,000	200,000
Less deferred debt issue costs		(4,300)	(5,500)	$ (2,800)
6.0% Senior Notes Due 2022
Debt Instrument [Line Items]
Senior notes		$ 300,000	$ 300,000

[1] There were no current portions of long-term debt as of December 31, 2016 and 2015.