Segment Reporting (Geographic Data) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Revenues	$ 1,357,801	$ 1,398,021	$ 1,381,370	$ 1,336,164	$ 1,363,877	$ 1,404,113	$ 1,446,096	$ 1,366,161	$ 5,473,356	$ 5,580,247	$ 5,289,953
United States [Member]
Segment Reporting Information [Line Items]
Revenues									5,094,193	5,189,792	4,965,630
Canada [Member]
Segment Reporting Information [Line Items]
Revenues									116,491	114,451	110,799
Other Countries [Member]
Segment Reporting Information [Line Items]
Revenues									$ 262,672	$ 276,004	$ 213,524