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	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Finance lease expense:
Amortization of right-of-use assets	$ 548	$ 1,551
Interest on lease liabilities	34	65
Operating lease expense	846	2,560
Total lease expense	1,428	4,176
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows from finance leases	34	65
Operating cash outflows from operating leases	821	2,484
Financing cash outflows from finance leases	381	1,035
Right-of-use assets obtained in exchange for new finance lease liabilities, net of terminations and disposals	1,292	1,803
Right-of-use assets obtained in exchange for operating lease liabilities (including adoption impact of $18.2 million) net of terminations and disposals	12	18,353
Operating leases:
Other non-current assets	15,079	15,079
Accrued liabilities	(2,694)	(2,694)
Other non-current liabilities	(13,508)	(13,508)
Total operating lease liabilities	(16,202)	(16,202)
Property and equipment gross	4,109	4,109
Accumulated depreciation	(1,677)	(1,677)
Property and equipment, net	2,432	2,432
Current portion of long-term debt	(328)	(328)
Long-term debt	(1,472)	(1,472)
Total finance lease liabilities	$ (1,800)	$ (1,800)
Weighted-average remaining lease term - finance leases (years)	4 years 4 months 24 days	4 years 4 months 24 days
Weighted-average remaining lease term - operating leases (years)	6 years 8 months 12 days	6 years 8 months 12 days
Weighted-average discount rate - finance leases	2.90%	2.90%
Weighted-average discount rate - operating leases	4.00%	4.00%