Segment Information (Total Revenues of Reportable Segments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Total Revenue [Line Items]
Total revenues	$ 2,389,815	$ 2,449,081	$ 7,581,559	$ 7,117,809
US Segment Reporting Information [Member]
Segment Total Revenue [Line Items]
Total revenues	1,337,562	1,446,834	4,402,212	4,141,202
Canada Segment Reporting Information [Member]
Segment Total Revenue [Line Items]
Total revenues	292,504	287,629	884,918	839,491
Europe And South Africa Segment Reporting Information [Member]
Segment Total Revenue [Line Items]
Total revenues	358,796	323,225	1,036,935	955,505
Asia Pacific Segment Reporting Information [Member]
Segment Total Revenue [Line Items]
Total revenues	376,929	364,516	1,134,071	1,101,934
Corporate And Other Segment Reporting Information [Member]
Segment Total Revenue [Line Items]
Total revenues	$ 24,024	$ 26,877	$ 123,423	$ 79,677