Segment Information (Details 2) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Segment Total Assets [Line Items]
Total assets	$ 40,197,101,000	$ 40,360,438,000
US Segment Reporting Information [Member]
Segment Total Assets [Line Items]
Total assets	24,802,143,000	24,924,363,000
Canada Segment Reporting Information [Member]
Segment Total Assets [Line Items]
Total assets	3,946,500,000	3,764,002,000
Europe And South Africa Segment Reporting Information [Member]
Segment Total Assets [Line Items]
Total assets	2,137,397,000	2,235,199,000
Asia Pacific Segment Reporting Information [Member]
Segment Total Assets [Line Items]
Total assets	3,051,842,000	3,208,732,000
Corporate And Other Segment Reporting Information [Member]
Segment Total Assets [Line Items]
Total assets	$ 6,259,219,000	$ 6,228,142,000