Fair Value Significant unobservable inputs (Level 3) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Assets Liabilites Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ (7)	$ (2)	$ (7)	$ (2)	$ (31)	$ (1)	$ 18	$ 3
Total gains (losses), Included in earnings	15	(14)	(3)	(8)
Total gains (losses), Included in other comprehensive income	10	(2)	0	(2)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Liability Net, Purchases	0	0	0	18
Settlements	(1)	(4)	(3)	(13)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 16	$ (13)	$ (4)	$ (11)