Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Total gain (loss) to be reclassified during next 12 months	$ (50)
Maximum Length of Time Hedged in Foreign Currency Cash Flow Hedge		16 years
Maximum Length of Time Hedged in Interest Rate Cash Flow Hedge		18 years
Margin cash collateral received from counterparties that was not offset against derivative assets	15	15	24
Margin cash collateral provided to counterparties that was not offset against derivative liabilities	$ 182	$ 182	$ 42