Revenue (Disaggregation of Revenue by Geographical Areas) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of revenue
Revenues	$ 621,787	$ 618,264	$ 627,533	$ 596,117	$ 646,365	$ 629,735	$ 619,130	$ 562,684	$ 2,463,701	$ 2,457,914	$ 2,116,737
United States
Disaggregation of revenue
Revenues									2,191,560	2,145,098	1,837,525
Mexico
Disaggregation of revenue
Revenues									197,470	233,116	210,228
Other
Disaggregation of revenue
Revenues									$ 74,671	$ 79,700	$ 68,984