Share-Based Compensation (Details 3) (Nonvested stock awards, USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Nonvested Stock Shares
Nonvested at the beginning of the period (in shares)	4,868,017	4,697,209
Granted (in shares)		1,632,699
Vested (in shares)		(1,427,409)
Forfeited (in shares)		(34,482)
Nonvested at the end of the period (in shares)		4,868,017	4,697,209
Nonvested Stock Shares, Weighted Average Grant Date Fair Value
Nonvested at the beginning of the period (in dollars per share)	$ 31.52	$ 27.86
Granted (in dollars per share)		$ 36.19
Vested (in dollars per share)		$ 24.83
Forfeited (in dollars per share)		$ 30.42
Nonvested at the end of the period (in dollars per share)		$ 31.52	$ 27.86
Compensation expense		$ 46,500,000	$ 40,300,000	$ 30,500,000
Related income tax benefit recognized		17,100,000	14,900,000	11,200,000
Remaining unamortized expense of nonvested stock expected to be recognized		101,900,000
Weighted average period for recognition of remaining unamortized expense (in years)		2.3
Total fair value of shares vested		52,500,000	46,500,000	23,300,000
Shares expected to be repurchased from employees who elect to tender shares to cover minimum tax withholdings	575,000
ACF
Nonvested Stock Shares, Weighted Average Grant Date Fair Value
Compensation expense				$ 400,000