Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Maximum Length of Time Hedged in Interest Rate Cash Flow Hedge		18 years 3 months
Maximum Length of Time Hedged in Foreign Currency Cash Flow Hedge		16 years 3 months
Total gain (loss) to be reclassified during next 12 months	$ (49)
Margin cash collateral received from counterparties that was not offset against derivative assets	20	20	24
Margin cash collateral provided to counterparties that was not offset against derivative liabilities	$ 93	$ 93	$ 42