Long-term Debt - Schedule of Maturities of Debt (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Notes payable maturity date	2025-03
Minimum [Member]
Debt Instrument [Line Items]
Notes payable Interest rate	4.00%
Maximum [Member]
Debt Instrument [Line Items]
Notes payable Interest rate	5.00%
Term Loan Agreement [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 4,940	$ 5,146
Vehicle and Equipment [Member]
Debt Instrument [Line Items]
Notes payable maturity date	2023-03
Vehicle and Equipment [Member] | Minimum [Member]
Debt Instrument [Line Items]
Notes payable Interest rate	2.00%
Vehicle and Equipment [Member] | Maximum [Member]
Debt Instrument [Line Items]
Notes payable Interest rate	4.50%