Share-Based Compensation (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Y
Share Based Compensation Expense (Textual) [Abstract]
Vesting period for stock option from the date of grant	One to three years
Option term (in years)	10
Vesting period for outstanding restricted common stock from the date of grant	3 years
Unearned compensation expense, before income taxes due 2012	$ 71
Unearned compensation expense, before income taxes due 2013	43
Unearned compensation expense, before income taxes due 2014	4
Intrinsic value for outstanding option	51
Intrinsic value for exercisable option	$ 51
Weighted average remaining term of exercisable option	5