Capital Stock (Details 5) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Restricted Stock [Member]
Restricted Stock and Conditional Restricted Stock Award
Restricted Shares, nonvested, Beginning Balance, Shares	2,210,000
Non-vested at January1, 2011, Weighted Average Grant Date Fair Value	$ 100.72
Granted, Shares	887,851	1,143,989	1,119,936
Granted, Weighted Average Grant-Date Fair Value	$ 124.16	$ 103.88	$ 84.30
Vested, Shares	(829,000)
Vested, Weighted Average Grant-Date Fair Value	$ 102.12
Forfeited or cancelled, Shares	(154,000)
Forfeited, Weighted Average Grant-Date Fair Value	$ 86.61
Restricted Shares, nonvested, Ending Balance, Shares	2,115,000	2,210,000
Non-vested at December 31, 2011, Weighted Average Grant Date Fair Value	$ 109.31	$ 100.72
Conditional Restricted Stock [Member]
Restricted Stock and Conditional Restricted Stock Award
Restricted Shares, nonvested, Beginning Balance, Shares	523,000
Non-vested at January1, 2011, Weighted Average Grant Date Fair Value	$ 141.86
Granted, Shares	586,000
Granted, Weighted Average Grant-Date Fair Value	$ 91.29
Vested, Shares	2,000
Vested, Weighted Average Grant-Date Fair Value	$ 118.31
Forfeited or cancelled, Shares	(88,000)
Forfeited, Weighted Average Grant-Date Fair Value	$ 115.67
Restricted Shares, nonvested, Ending Balance, Shares	1,019,000
Non-vested at December 31, 2011, Weighted Average Grant Date Fair Value	$ 115.10