Segment Information (Details 2) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Segment Total Assets [Line Items]
Total assets	$ 30,659,277	$ 29,081,908
US Segment Reporting Information Member
Segment Total Assets [Line Items]
Total assets	17,612,924	17,470,744
Canada Segment Reporting Information Member
Segment Total Assets [Line Items]
Total assets	3,682,535	3,441,915
Europe And South Africa Segment Reporting Information Member
Segment Total Assets [Line Items]
Total assets	1,795,122	1,584,007
Asia Pacific Segment Reporting Information Member
Segment Total Assets [Line Items]
Total assets	2,921,825	2,440,316
Corporate And Other Segment Reporting Information Member
Segment Total Assets [Line Items]
Total assets	$ 4,646,871	$ 4,144,926