Derivatives (Fair Value Hedges) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	$ (297)	$ 57	$ (981)
Net Derivative Gains (Losses) Recognized for Hedged Items	285	(79)	992
Ineffectiveness Recognized in Net Derivative Gains (Losses)	(12)	(22)	11
Interest rate swaps \| Fixed Maturity Securities
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	5	5	42
Net Derivative Gains (Losses) Recognized for Hedged Items	0	(1)	(43)
Ineffectiveness Recognized in Net Derivative Gains (Losses)	5	4	(1)
Interest rate swaps \| Policyholder account balances [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(2)	681	(830)
Net Derivative Gains (Losses) Recognized for Hedged Items	(8)	(667)	835
Ineffectiveness Recognized in Net Derivative Gains (Losses)	(10)	14	5
Foreign currency swaps \| Foreign-denominated fixed maturity securities
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	15	13	13
Net Derivative Gains (Losses) Recognized for Hedged Items	(7)	(11)	(12)
Ineffectiveness Recognized in Net Derivative Gains (Losses)	8	2	1
Foreign currency swaps \| Foreign-denominated policyholder account balances [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(240)	(283)	(97)
Net Derivative Gains (Losses) Recognized for Hedged Items	232	270	110
Ineffectiveness Recognized in Net Derivative Gains (Losses)	(8)	(13)	13
Foreign currency forwards \| Foreign-denominated fixed maturity securities
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(75)	(359)	(109)
Net Derivative Gains (Losses) Recognized for Hedged Items	68	330	102
Ineffectiveness Recognized in Net Derivative Gains (Losses)	$ (7)	$ (29)	$ (7)

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

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