Leases - Summary of Minimum Future Capital and Operating Leases Payments (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 2,075
Capital Leases, Future Minimum Payments Due, Next Twelve Months	1,021
Operating Leases, Future Minimum Payments, Due in Two Years	1,762
Capital Leases, Future Minimum Payments Due in Two Years	1,184
Operating Leases, Future Minimum Payments, Due in Three Years	346
Capital Leases, Future Minimum Payments Due in Three Years	1,384
Operating Leases, Future Minimum Payments, Due in Four Years	149
Capital Leases, Future Minimum Payments Due in Four Years	1,584
Operating Leases, Future Minimum Payments, Due in Five Years	15
Capital Leases, Future Minimum Payments Due in Five Years	1,584
Operating Leases, Future Minimum Payments, Due Thereafter	0
Capital Leases, Future Minimum Payments Due Thereafter	42,300
Operating Leases, Future Minimum Payments Due	4,347
Capital Leases, Future Minimum Payments Due	$ 49,057