Employee Benefit Plans (Estimated Amortization of Unamortized Actuarial Gains and Losses - 2015) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
Qualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit)	$ (9,000,000)
Net actuarial loss	29,000,000
Total estimated amortization of unamortized actuarial gains and losses	20,000,000
Nonqualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	8,000,000
Total estimated amortization of unamortized actuarial gains and losses	8,000,000
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit)	(1,000,000)
Total estimated amortization of unamortized actuarial gains and losses	$ (1,000,000)