Revenue - Summary of Asset Balances and Related Amortization Expense For Contract Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Costs to Obtain a Contract [Member]
Capitalized Contract Cost [Line Items]
Beginning Balance	$ 248,908	$ 209,462	$ 232,583	$ 194,964
Capitalization of Costs	16,648	12,174	50,890	41,340
Amortization	(9,469)	(7,716)	(27,386)	(22,384)
Ending Balance	256,087	213,920	256,087	213,920
Costs to Fulfill a Contract [Member]
Capitalized Contract Cost [Line Items]
Beginning Balance	229,512	171,941	199,593	143,788
Capitalization of Costs	24,652	18,709	68,764	57,289
Amortization	(7,931)	(5,889)	(22,124)	(16,316)
Ending Balance	$ 246,233	$ 184,761	$ 246,233	$ 184,761