Derivatives - Fair Value Hedges - Non-qualifying Strategies (Details) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended	5 Months Ended	6 Months Ended
	Jun. 30, 2018	May 31, 2018	Jun. 30, 2017	May 31, 2018	Jun. 30, 2017
Total other non-qualifying derivatives
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	$ (1)	$ (5)		$ (10)
Not Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	(2)	(61)	$ (32)	(27)	$ (81)
Not Designated as Hedging Instrument | Fair Value Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	7	(46)	(18)	(24)	(86)
Not Designated as Hedging Instrument | GMWB Product Derivatives [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	8	43	39	82	140
Not Designated as Hedging Instrument | GMWB Reinsurance [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	(1)	(12)	(6)	(25)	(24)
Not Designated as Hedging Instrument | GMWB Hedging Instruments [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	0	(23)	(13)	(45)	(78)
Not Designated as Hedging Instrument | Macro Hedge Program [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	0	(54)	(38)	(36)	(124)
Not Designated as Hedging Instrument | Foreign Currency Swaps and Forwards [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	0	0	1	(3)	(3)
Not Designated as Hedging Instrument | Fixed Annuity Hedging Instruments [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	(8)	(10)	(10)	10	11
Not Designated as Hedging Instrument | Foreign Exchange Forward [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	(8)	(10)	(9)	7	8
Not Designated as Hedging Instrument | Interest rate swaps, swaptions and futures
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	(9)	(10)	6	(40)	8
Not Designated as Hedging Instrument | Credit Risk Contract [Member] | Credit derivatives that purchase credit protection
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	0	1	18	1	12
Not Designated as Hedging Instrument | Credit Risk Contract [Member] | Credit derivatives that assume credit risk
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	0	(2)	(16)	(3)	(9)
Not Designated as Hedging Instrument | Equity index options
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	0	0	(5)	0	(4)
Not Designated as Hedging Instrument | Other Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives	$ 8	$ 6	(8)	$ 32	(10)
Not Designated as Hedging Instrument | Total other non-qualifying derivatives
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Non-qualifying foreign currency derivatives			$ (5)		$ (3)