Revenue (Tables)

9 Months Ended

Sep. 30, 2019

Revenue From Contract With Customer [Abstract]

Summary of Changes in Deferred Revenue Related to Material Right Performance Obligations

Changes in deferred revenue related to material right performance obligations as of September 30, 2019 and 2018 were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Balance, beginning of period	$	70,004		$	57,189		$	64,651		$	51,624
Deferral of revenue		6,631			5,643			17,651			14,902
Recognition of unearned revenue		(3,270	)		(2,018	)		(8,937	)		(5,712	)
Balance, end of period	$	73,365		$	60,814		$	73,365		$	60,814

Summary of Asset Balances and Related Amortization Expense For Contract Costs

The following tables present the asset balances and related amortization expense for these contract costs:

	As of and for the Three Months Ended September 30, 2019
	Beginning		Capitalization					Ending
	Balance		of Costs		Amortization			Balance
Costs to obtain a contract	$	178,445	$	11,315	$	(6,321	)	$	183,439
Costs to fulfill a contract	$	121,664	$	15,323	$	(4,258	)	$	132,729
	As of and for the Three Months Ended September 30, 2018
	Beginning		Capitalization					Ending
	Balance		of Costs		Amortization			Balance
Costs to obtain a contract	$	140,119	$	10,595	$	(4,855	)	$	145,859
Costs to fulfill a contract	$	87,199	$	9,730	$	(3,001	)	$	93,928
	As of and for the Nine Months Ended September 30, 2019
	Beginning		Capitalization					Ending
	Balance		of Costs		Amortization			Balance
Costs to obtain a contract	$	158,989	$	42,513	$	(18,063	)	$	183,439
Costs to fulfill a contract	$	101,756	$	42,614	$	(11,641	)	$	132,729
	As of and for the Nine Months Ended September 30, 2018
	Beginning		Capitalization					Ending
	Balance		of Costs		Amortization			Balance
Costs to obtain a contract	$	126,207	$	33,565	$	(13,913	)	$	145,859
Costs to fulfill a contract	$	72,061	$	30,156	$	(8,289	)	$	93,928