Separation of Brighthouse (Effects of Affiliated Reinsurance on Balance Sheets) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Assets [Abstract]
Premiums, reinsurance and other receivables relating to variable interest entities	$ 19,368	$ 18,423
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	19,330	18,419
Liabilities [Abstract]
Liability for Future Policy Benefits	180,348	177,974
Other Policy-Related Balances	16,023	15,515
Other Liabilities	24,013	23,982
Assumed Reinsurance [Member] | Affiliated Entity [Member]
Assets [Abstract]
Premiums, reinsurance and other receivables relating to variable interest entities	154	167
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	390	384
Reinsurance Assets	544	551
Liabilities [Abstract]
Liability for Future Policy Benefits	1,788	1,734
Other Policy-Related Balances	116	119
Other Liabilities	1,447	1,458
Reinsurance Liabilities	3,351	3,311
Ceded Reinsurance [Member] | Affiliated Entity [Member]
Assets [Abstract]
Premiums, reinsurance and other receivables relating to variable interest entities	1,802	1,793
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	(40)	(40)
Reinsurance Assets	1,762	1,753
Liabilities [Abstract]
Liability for Future Policy Benefits	0	0
Other Policy-Related Balances	25	28
Other Liabilities	25	19
Reinsurance Liabilities	$ 50	$ 47