Employee Benefit Benefits and Stock-Based Compensation - Annual Discretionary Bonus Grant (Details) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2015
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits
Defined Contribution Plan, Maximum Annual Contribution Per Employee	$ 17,500
Accrued Bonuses, Current	167,000,000	124,000,000	103,000,000
Cash Payments for Employee Bonus		57,000,000	50,000,000
Expected Percent of Bonus Paid in Cash	100.00%
Restricted Stock Unit Bonus Grant
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		1.4	2.1
Subsequent Event [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits
Defined Contribution Plan, Maximum Annual Contribution Per Employee				$ 18,000