Dispositions - Separation of Brighthouse - Ongoing Reinsurance Transactions (Effects of Reinsurance on Earnings) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Premiums:
Reinsurance assumed	$ 1,773	$ 1,363	$ 1,382
Reinsurance ceded	(2,376)	(2,136)	(2,023)
Net premiums	38,992	37,202	36,403
Fees and Commissions [Abstract]
Assumed Insurance Commissions And Fees	83	96	105
Ceded Insurance Commissions And Fees	551	497	487
Net universal life and investment product policy fees	5,510	5,483	5,570
Policyholder benefits and claims:
Reinsurance assumed	1,388	1,085	984
Reinsurance ceded	(2,429)	(1,913)	(1,983)
Net policyholder benefits and claims	38,313	36,358	35,144
Interest Credited To Policyholder Account Balances [Abstract]
Interest Credited to Policyholders Account Balances	5,607	5,176	4,415
Other expenses:
Reinsurance assumed	246	169	146
Reinsurance ceded	235	378	303
Total other expenses	13,621	13,749	14,777
Affiliated Entity [Member] | Assumed Reinsurance [Member]
Premiums:
Reinsurance assumed	183
Fees and Commissions [Abstract]
Assumed Insurance Commissions And Fees	(4)
Policyholder benefits and claims:
Reinsurance assumed	150
Interest Credited To Policyholder Account Balances [Abstract]
Assumed Interest Credited To Policyholders Account Balances	6
Other expenses:
Reinsurance assumed	39
Affiliated Entity [Member] | Ceded Reinsurance [Member]
Premiums:
Reinsurance ceded	(4)
Fees and Commissions [Abstract]
Ceded Insurance Commissions And Fees	44
Policyholder benefits and claims:
Reinsurance ceded	(22)
Interest Credited To Policyholder Account Balances [Abstract]
Ceded Interest Credited To Policyholders Account Balances	30
Other expenses:
Reinsurance ceded	7
Affiliated Entity [Member] | Reinsurance [Member]
Premiums:
Net premiums	179
Fees and Commissions [Abstract]
Net universal life and investment product policy fees	(48)
Policyholder benefits and claims:
Net policyholder benefits and claims	128
Interest Credited To Policyholder Account Balances [Abstract]
Interest Credited to Policyholders Account Balances	(24)
Other expenses:
Total other expenses	46
Brighthouse Financial, Inc [Member] | Assumed Reinsurance [Member]
Premiums:
Reinsurance assumed	248	462	416
Fees and Commissions [Abstract]
Assumed Insurance Commissions And Fees	(6)	(2)	2
Policyholder benefits and claims:
Reinsurance assumed	196	385	330
Interest Credited To Policyholder Account Balances [Abstract]
Assumed Interest Credited To Policyholders Account Balances	10	16	14
Other expenses:
Reinsurance assumed	10	88	76
Brighthouse Financial, Inc [Member] | Ceded Reinsurance [Member]
Premiums:
Reinsurance ceded	(7)	(9)	(8)
Fees and Commissions [Abstract]
Ceded Insurance Commissions And Fees	55	102	114
Policyholder benefits and claims:
Reinsurance ceded	(16)	(23)	(28)
Interest Credited To Policyholder Account Balances [Abstract]
Ceded Interest Credited To Policyholders Account Balances	42	75	78
Other expenses:
Reinsurance ceded	(28)	(29)	(45)
Brighthouse Financial, Inc [Member] | Reinsurance [Member]
Premiums:
Net premiums	241	453	408
Fees and Commissions [Abstract]
Net universal life and investment product policy fees	(61)	(104)	(112)
Policyholder benefits and claims:
Net policyholder benefits and claims	180	362	302
Interest Credited To Policyholder Account Balances [Abstract]
Interest Credited to Policyholders Account Balances	(32)	(59)	(64)
Other expenses:
Total other expenses	$ (18)	$ 59	$ 31