Investments (Changes in Fixed Maturity Securities with Noncredit OTTI Losses) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Changes in fixed maturity securities with noncredit OTTI losses in accumulated other comprehensive income (loss)
Balance, beginning of period	$ (218)	$ (361)
Noncredit OTTI losses recognized	2	60
Securities sold with a previous noncredit OTTI loss	25	149
Subsequent increases in estimated fair value	81	(66)
Balance, end of period	$ (110)	$ (218)