Segment Information (Schedule Of Revenue And Long-Lived Assets, By Geographical Areas) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 528,783	$ 534,448	$ 534,644	$ 495,654	$ 553,186	$ 551,961	$ 542,120	$ 492,022	$ 2,093,529	$ 2,139,289	$ 2,029,183
Long-lived assets	1,154,470				1,013,782				1,154,470	1,013,782	977,518
United States [Member]
Segment Reporting Information [Line Items]
Revenues									1,821,026	1,857,624	1,768,442
Long-lived assets	1,134,433				989,815				1,134,433	989,815	955,543
Mexico [Member]
Segment Reporting Information [Line Items]
Revenues									191,453	187,124	172,009
Long-lived assets	19,879				23,734				19,879	23,734	21,654
Other [Member]
Segment Reporting Information [Line Items]
Revenues									81,050	94,541	88,732
Long-lived assets	158				233				158	233	321
Total Foreign Countries [Member]
Segment Reporting Information [Line Items]
Revenues									272,503	281,665	260,741
Long-lived assets	$ 20,037				$ 23,967				$ 20,037	$ 23,967	$ 21,975