Separation of Brighthouse (Effects of Affiliated Reinsurance on Balance Sheets) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Assets [Abstract]
Premiums, reinsurance and other receivables relating to variable interest entities	$ 19,608	$ 18,423
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	19,013	18,419
Liabilities [Abstract]
Liability for Future Policy Benefits	184,461	177,974
Other Policy-Related Balances	15,908	15,515
Other Liabilities	24,930	23,982
Assumed Reinsurance [Member] | Affiliated Entity [Member]
Assets [Abstract]
Premiums, reinsurance and other receivables relating to variable interest entities	157	167
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	381	384
Reinsurance Assets	538	551
Liabilities [Abstract]
Liability for Future Policy Benefits	1,842	1,734
Other Policy-Related Balances	120	119
Other Liabilities	1,446	1,458
Reinsurance Liabilities	3,408	3,311
Ceded Reinsurance [Member] | Affiliated Entity [Member]
Assets [Abstract]
Premiums, reinsurance and other receivables relating to variable interest entities	1,788	1,793
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	(40)	(40)
Reinsurance Assets	1,748	1,753
Liabilities [Abstract]
Liability for Future Policy Benefits	0	0
Other Policy-Related Balances	22	28
Other Liabilities	16	19
Reinsurance Liabilities	$ 38	$ 47