Derivatives (Cash Flow Hedges) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Average Remaining Maturity	4 years 4 months	4 years 5 months
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in AOCI	$ 414
Cash Flow Hedges [Member]
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in AOCI	(47)	$ 273	$ (121)
Cash Flow Hedges [Member] | Interest rate swaps
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in AOCI	78	50	76
Cash Flow Hedges [Member] | Foreign currency swaps
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in AOCI	(335)	589	(194)
Cash Flow Hedges [Member] | Interest rate forwards
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in AOCI	210	(366)	(3)
Cash Flow Hedges [Member] | Credit forwards
Derivatives in cash flow hedging relationships
Amount of Gains (Losses) Deferred in AOCI	0	0	0
Cash Flow Hedges [Member] | Net derivative gains (losses)
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	988	(292)	(631)
Amount and Location of Gains (Losses) Recognized In Income (Loss) on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	12	0	11
Cash Flow Hedges [Member] | Net derivative gains (losses) | Interest rate swaps
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	24	56	84
Amount and Location of Gains (Losses) Recognized In Income (Loss) on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	18	(1)	2
Cash Flow Hedges [Member] | Net derivative gains (losses) | Foreign currency swaps
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	974	(350)	(720)
Amount and Location of Gains (Losses) Recognized In Income (Loss) on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	(4)	1	9
Cash Flow Hedges [Member] | Net derivative gains (losses) | Interest rate forwards
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	(11)	(1)	4
Amount and Location of Gains (Losses) Recognized In Income (Loss) on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	(2)	0	0
Cash Flow Hedges [Member] | Net derivative gains (losses) | Credit forwards
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	1	3	1
Amount and Location of Gains (Losses) Recognized In Income (Loss) on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	0	0
Cash Flow Hedges [Member] | Net Investment Income
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	18	15	13
Cash Flow Hedges [Member] | Net Investment Income | Interest rate swaps
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	16	12	11
Cash Flow Hedges [Member] | Net Investment Income | Foreign currency swaps
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	0	(2)	(1)
Cash Flow Hedges [Member] | Net Investment Income | Interest rate forwards
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	2	4	3
Cash Flow Hedges [Member] | Net Investment Income | Credit forwards
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	0	1	0
Cash Flow Hedges [Member] | Other expenses
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	3	3	3
Cash Flow Hedges [Member] | Other expenses | Interest rate swaps
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	0	0	0
Cash Flow Hedges [Member] | Other expenses | Foreign currency swaps
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	2	2	1
Cash Flow Hedges [Member] | Other expenses | Interest rate forwards
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	1	1	2
Cash Flow Hedges [Member] | Other expenses | Credit forwards
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	0	0	0
Brighthouse Financial, Inc [Member] | Discontinued Operations [Member] | Cash Flow Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Reduction of Deferred Gains within AOCI		71	102
Derivatives in cash flow hedging relationships
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	$ 16	$ 45	$ 7
B [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Average Remaining Maturity	4 years 11 months	4 years 4 months
B [Member] | Single name credit default swaps (3)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Average Remaining Maturity	3 years 6 months	1 year 10 months