Share-Based Payments (Details 8) (Time Vested Restricted Stock Units [Member], USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Time Vested Restricted Stock Units [Member]
Time-vested restricted stock units
Beginning Balance, Unvested, Shares	4,223,000
Beginning Balance, Weighted Average Grant Date Fair Value	$ 53.26
Shares, Granted	1,398,000
Weighted Average Grant Date Fair Value, Granted	$ 70.01	$ 54.79	$ 48.93
Shares, Vested	(1,980,000)
Weighted Average Grant Date Fair Value, Vested	$ 53.72
Shares, Forfeited	(717,000)
Weighted Average Grant Date Fair Value, Forfeited	$ 54.20
Ending Balance, Unvested, Shares	2,924,000	4,223,000
Ending Balance, Weighted Average Grant Date Fair Value	$ 60.72	$ 53.26