Summary of Required Compliance Ratios in Connection with Terms of Credit Agreement (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Debt Instrument [Line Items]
Covenant, Tangible net worth	$ 125,000
Tangible net worth	$ 191,372
Total leverage	44.30%
Secured leverage	16.10%
Unencumbered leverage	40.30%
Fixed charge coverage	3.70%
Maximum
Debt Instrument [Line Items]
Covenant, Total leverage	60.00%
Covenant, Secured leverage	30.00%
Covenant, Unencumbered leverage	60.00%
Minimum
Debt Instrument [Line Items]
Covenant, Fixed charge coverage	1.50%