Contract Assets (Tables)

9 Months Ended

Sep. 30, 2018

Contract With Customer Asset And Liability [Abstract]

Changes In Contract Assets

Significant changes in the contract asset balance during the period are as follows:

	Nine Months Ended
	September 30,
(in thousands)		2018		2017
Beginning balance as of December 31, 2017	$	146,496	$	156,206
Revenue recognized		1,774,620		1,667,090
Amounts collected or invoiced		(1,765,218)		(1,661,717)
Ending balance as of September 30, 2018	$	155,898	$	161,579