Long-Term Debt - Summary (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term debt, gross	$ 218,100	$ 170,003
Less current portion	0	3
Total long-term debt	218,100	170,000
Less debt issuance costs	2,045	3,104
Total long-term debt, net of debt issuance costs	$ 216,055	$ 166,896
Weighted-average interest rate (percent)	3.73%	3.25%
Term Loan
Debt Instrument [Line Items]
Long-term debt, gross	$ 160,000	$ 170,000
Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt, gross	58,100	0
Other Debt
Debt Instrument [Line Items]
Long-term debt, gross	$ 0	$ 3
Fixed rate (percent)	5.41%