Investments (Consolidated Variable Interest Entities - Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Variable Interest Entity [Line Items]
Tax credits guaranteed by third parties that reduce maximum exposure to loss related to other invested assets	$ 208		$ 212
Financial or other support to investees designated as VIEs	0	0
Consolidated Securitization Entities [Member]
Variable Interest Entity [Line Items]
Variable interest, maximum exposure to loss in consolidated securitization entities	122		123
Long-term debt held by consolidated securitization entities, percentage range minimum	2.25%	2.25%
Long-term debt held by consolidated securitization entities, percentage range maximum	5.57%	5.57%
Interest expense on long-term debt held by consolidated securitization entities	$ 1	$ 18