Employee Benefit Benefits and Stock-Based Compensation - Annual Discretionary Bonus Grant (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits
Accrued Bonuses, Current	$ 136	$ 59	$ 103
Cash Payments for Employee Bonus	$ 72	$ 29
Expected Percent Of Bonus Paid In Stock			60.00%
Expected Percent of Bonus Paid in Cash			40.00%
Restricted Stock Unit Bonus Grant | Restricted Stock Units and Shares
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted or Expected to Be Granted in Next Fiscal Period	2.4	1.7