Stock-Based Compensation (Stock Based Compensation Textuals) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013		Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		1.40%	[1]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate		25.60%	[2]
Vesting period for graded and cliff vesting options - minimum	1 year
Vesting period for graded and cliff vesting options - maximum	5 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Expiration Minimum Range	5 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Expiration Maximum Range	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized for Directors	567,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized for Employees	40,533,000
Percentage of sub-grants representing the total	33.33%
Vest Term of First Sub Grant	1 year
Vest Term of the Second Sub-Grant	2 years
Vest Term of the Third Sub-Grant	3 years
Grants in Option Grants with Three Year Cliff Vesting	1
Vesting term of option grants with three year cliff vesting	3 years
Allocated Share-based Compensation Expense	$ 9	$ 8
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	1	2
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options	3	9
Allocated Share Based Compensation Expense Liability Classified Share-Based Awards	1	0
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	1
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	10 months 25 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	4,735,696			4,431,841
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	47
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 8 months 13 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value	29	20
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	1,764,446
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 19.11
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 0
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 month 6 days
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	895,879			449,798
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	461,393
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 22.56

[1] Zero Coupon U.S. Treasury rate or equivalent based on expected term.

[2] Volatility calculated using the implied volatility of our exchange traded stock options.