Derivatives (Changes in Estimated Fair Value Related to Embedded Derivatives) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives gains (losses)	$ (27)	$ (109)
Net derivative gains (losses)
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives gains (losses)	(27)	(109)
Policyholder benefits and claims
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives gains (losses)	$ 24	$ 15