Revenue from Contracts with Customers - Summary of Significant Changes in Contract Assets and Contract Liabilities Balances (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)
Revenue From Contract With Customer [Abstract]
Contract assets at January 1, 2019	$ 8,939
Contract liabilities at January 1, 2019	(20,526)
Net balance at January 1, 2019	(11,587)
Decrease due to amortization of revenue included in the beginning contract liability balance	3,681
Increase due to cash received, excluding amounts recognized as revenue during the period	(17,698)
Increase due to revenue recognized during the period but contingent on future performance	2,535
Decrease due to transfer to receivables during the period	(926)
Adjustments	(1,044)
Net balance at June 30, 2019	(25,039)
Contract assets at June 30, 2019	9,505
Contract liabilities at June 30, 2019	$ (34,544)