Revenue (Tables)

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Summary of Total Receivables, Net

Total receivables, net is comprised of the following (in thousands):

	December 31,
	2019			2018
Billed receivables	$	213,654		$	239,275
Allowance for doubtful accounts	(5,149		)	(3,912		)
Billed receivables, net	208,505			235,363
Accrued receivables	399,302			336,858
Significant financing component	(35,569		)	(35,029		)
Total accrued receivables, net	363,733			301,829
Less: current accrued receivables	161,714			123,053
Less: current significant financing component	(11,022		)	(10,234		)
Total long-term accrued receivables, net	213,041			189,010
Total receivables, net	$	572,238		$	537,192

Summary of Allowance for Doubtful Accounts Receivable

The following reflects activity in the Company’s allowance for doubtful accounts receivable for the periods indicated (in thousands):

	Years Ended December 31,
	2019			2018			2017
Balance, beginning of period	$	(3,912	)	$	(4,799	)	$	(3,873	)
Provision increase	(2,561		)	(1,505		)	(2,086		)
Amounts written off, net of recoveries	1,368			2,269			1,305
Foreign currency translation adjustments and other	(44		)	123			(145		)
Balance, end of period	$	(5,149	)	$	(3,912	)	$	(4,799	)

Summary of Changes in Deferred Revenue

Changes in deferred revenue were as follows (in thousands):

Balance, January 1, 2018	$	145,344
Deferral of revenue	215,188
Recognition of deferred revenue	(200,061		)
Foreign currency translation	(4,336		)
Balance, December 31, 2018	156,135
Deferral of revenue	149,253
Recognition of deferred revenue	(187,069		)
Foreign currency translation	620
Balance, December 31, 2019	$	118,939