Leases - Schedule of Lease Expense, Cash Flow, Operating and Finance Lease Assets and Liabilities, Average Lease Term and Average Discount Rate (Detail) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Finance lease expense:
Amortization of right-of-use assets	$ 487	$ 1,003
Interest on lease liabilities	17	31
Operating lease expense	861	1,714
Total lease expense	1,365	2,748
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows from finance leases	17	31
Operating cash outflows from operating leases	835	1,663
Financing cash outflows from finance leases	329	654
Right-of-use assets obtained in exchange for new finance lease liabilities, net of terminations	(45)	511
Right-of-use assets obtained in exchange for operating lease liabilities (including adoption impact of $18.2 million)	56	18,341
Operating leases:
Other non-current assets	16,903	16,903
Accrued liabilities	(2,760)	(2,760)
Other non-current liabilities	(14,554)	(14,554)
Total operating lease liabilities	(17,314)	(17,314)
Property and equipment gross	4,612	4,612
Accumulated depreciation	(1,673)	(1,673)
Property and equipment, net	2,939	2,939
Current portion of long-term debt	(708)	(708)
Long-term debt	(1,626)	(1,626)
Total finance lease liabilities	$ (2,334)	$ (2,334)
Weighted-average remaining lease term - finance leases (years)	2 years 7 months 6 days	2 years 7 months 6 days
Weighted-average remaining lease term - operating leases (years)	7 years 3 months 18 days	7 years 3 months 18 days
Weighted-average discount rate - finance leases	2.80%	2.80%
Weighted-average discount rate - operating leases	4.00%	4.00%