Derivatives Derivatives (NQ, CF, FV) (Details) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Derivative [Line Items]
Maximum Length of Time Hedged in Cash Flow Hedge			1 year		2 years
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	$ (2)	$ (2)	$ 8	$ (42)
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	108	(32)	35	(51)
Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	2	0	3	2
Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(313)	(154)	(663)	(1,046)
Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1)	(76)	(2)	(276)
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	(5)	2	(2)	(32)
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	0	0	0	0
Not Designated as Hedging Instrument [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(1)	0	(1)
Not Designated as Hedging Instrument [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(320)	(158)	(669)	(1,056)
Not Designated as Hedging Instrument [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1)	(76)	(2)	(276)
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	0	0	0	0
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	0	0	0	0
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(165)	205	(974)	(64)
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	3	0	2
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	(5)	2	(2)	(32)
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	0	0	0	0
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	56	(22)	15	(42)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Credit Risk Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	0	0	0	0
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	0	0	0	0
Credit Risk Contract [Member] | Not Designated as Hedging Instrument [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Credit Risk Contract [Member] | Not Designated as Hedging Instrument [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(3)	5	(10)	11
Credit Risk Contract [Member] | Not Designated as Hedging Instrument [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Equity Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	0	0	0	0
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	0	0	0	0
Equity Contract [Member] | Not Designated as Hedging Instrument [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(1)	0	(1)
Equity Contract [Member] | Not Designated as Hedging Instrument [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(440)	(474)	(484)	(1,412)
Equity Contract [Member] | Not Designated as Hedging Instrument [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(93)	0	(277)
Embedded Derivative Financial Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	0	0	0	0
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	0	0	0	0
Embedded Derivative Financial Instruments [Member] | Not Designated as Hedging Instrument [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Embedded Derivative Financial Instruments [Member] | Not Designated as Hedging Instrument [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	232	128	784	451
Embedded Derivative Financial Instruments [Member] | Not Designated as Hedging Instrument [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1)	14	(2)	(1)
Fair Value Hedging [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	3	(3)	10	(1)
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	0	0	0	0
Fair Value Hedging [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Fair Value Hedging [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(2)	3	(10)	1
Fair Value Hedging [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	3	(3)	10	(1)
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	0	0	0	0
Fair Value Hedging [Member] | Interest Rate Contract [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Fair Value Hedging [Member] | Interest Rate Contract [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(2)	3	(10)	1
Fair Value Hedging [Member] | Interest Rate Contract [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Cash Flow Hedging [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	0	(1)	0	(9)
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	108	(32)	35	(51)
Cash Flow Hedging [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	2	1	3	3
Cash Flow Hedging [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	9	1	16	9
Cash Flow Hedging [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	0	0	0	0
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	0	1	(2)	1
Cash Flow Hedging [Member] | Interest Rate Contract [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	2	1	3	3
Cash Flow Hedging [Member] | Interest Rate Contract [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	10	0	17	0
Cash Flow Hedging [Member] | Interest Rate Contract [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Cash Flow Hedging [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	0	(1)	0	(9)
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives Effective Portion	108	(33)	37	(52)
Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | Net investment income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | Net Derivative Gain (Loss) [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1)	1	(1)	9
Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | Policyholder benefits and claims
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 0	$ 0	$ 0	$ 0