Derivatives (Details 5) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Offsetting of Financial Assets under Master Netting Agreements with Derivative Counterparties
Gross Amounts of Derivative Assets Presented in the Consolidated Balance Sheet	$ 76	$ 84
Net Amounts of Derivative Assets	47	33
Derivatives Subject to Master Netting Agreements
Offsetting of Financial Assets under Master Netting Agreements with Derivative Counterparties
Gross Amounts of Derivative Assets Presented in the Consolidated Balance Sheet	74	83
Gross Amount of Eligible Offsetting Recognized Derivative Liabilities	29	51
Cash Collateral Received	0	0
Net Amounts of Derivative Assets	45	32
Derivatives Not Subject to Master Netting Agreements
Offsetting of Financial Assets under Master Netting Agreements with Derivative Counterparties
Gross Amounts of Derivative Assets Presented in the Consolidated Balance Sheet	2	1
Net Amounts of Derivative Assets	$ 2	$ 1