Segment Information (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Segment Total Revenue [Line Items]
Total revenues	$ 2,203,977	$ 1,931,877	$ 4,486,412	$ 4,032,062
US Segment Reporting Information Member
Segment Total Revenue [Line Items]
Total revenues	1,254,057	1,187,111	2,606,197	2,473,702
Canada Segment Reporting Information Member
Segment Total Revenue [Line Items]
Total revenues	263,067	221,256	528,576	474,027
Europe And South Africa Segment Reporting Information Member
Segment Total Revenue [Line Items]
Total revenues	295,694	219,743	576,016	446,524
Asia Pacific Segment Reporting Information Member
Segment Total Revenue [Line Items]
Total revenues	346,120	282,181	685,325	592,037
Corporate And Other Segment Reporting Information Member
Segment Total Revenue [Line Items]
Total revenues	$ 45,039	$ 21,586	$ 90,298	$ 45,772