Debt - Carrying Value of Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Debt issuance costs	$ (9,823)	$ (10,521)
Total debt	679,240	685,729
Current portion of long-term debt	20,379	17,786
Less current portion of debt issuance costs	(2,965)	(2,964)
Total long-term debt	658,861	667,943
6.375% Senior Notes, due August 2020 [Member]
Debt Instrument [Line Items]
Total debt	300,000	300,000
Term Credit Facility [Member]
Debt Instrument [Line Items]
Total debt	389,063	394,250
Current portion of long-term debt	$ 23,344	20,750
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Total debt		$ 2,000