Segment Information (Schedule Of Revenue And Long-Lived Assets, 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
Segment Reporting Information [Line Items]
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
Long-lived assets	1,526,276				1,487,562				1,526,276	1,487,562	1,346,863
United States
Segment Reporting Information [Line Items]
Revenues									2,191,560	2,145,098	1,837,525
Long-lived assets	1,487,591				1,452,532				1,487,591	1,452,532	1,321,206
Mexico
Segment Reporting Information [Line Items]
Revenues									197,470	233,116	210,228
Long-lived assets	38,428				34,741				38,428	34,741	25,309
Other
Segment Reporting Information [Line Items]
Revenues									74,671	79,700	68,984
Long-lived assets	257				289				257	289	348
Total Foreign Countries [Member]
Segment Reporting Information [Line Items]
Revenues									272,141	312,816	279,212
Long-lived assets	$ 38,685				$ 35,030				$ 38,685	$ 35,030	$ 25,657