Revenue (Schedule of Significant Changes in Contract Assets) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Change In Contract With Customer Asset [Abstract]
Beginning balance as of December 31	$ 142,779	$ 161,061
Revenue recognized	944,052	915,600
Amounts collected or invoiced	(932,202)	(923,020)
Ending balance as of June 30	$ 154,629	$ 153,641