Segment Information (Schedule Of Revenue And Long-Lived Assets, By Geographical Areas) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 553,186	$ 551,961	$ 542,120	$ 492,022	$ 517,920	$ 511,728	$ 506,648	$ 492,887	$ 2,139,289	$ 2,029,183	$ 2,036,386
Long-lived Assets	1,013,782				977,518				1,013,782	977,518	993,843
United States [Member]
Segment Reporting Information [Line Items]
Revenues									1,857,624	1,768,442	1,772,179
Long-lived Assets	989,815				955,543				989,815	955,543	979,798
Mexico [Member]
Segment Reporting Information [Line Items]
Revenues									187,124	172,009	172,016
Long-lived Assets	23,734				21,654				23,734	21,654	13,659
Other [Member]
Segment Reporting Information [Line Items]
Revenues									94,541	88,732	92,191
Long-lived Assets	233				321				233	321	386
Total Foreign Countries [Member]
Segment Reporting Information [Line Items]
Revenues									281,665	260,741	264,207
Long-lived Assets	$ 23,967				$ 21,975				$ 23,967	$ 21,975	$ 14,045