Effects of Affiliated Reinsurance on Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Assets [Abstract]
Premiums, reinsurance and other receivables relating to variable interest entities	$ 18,588	$ 15,445
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	18,399	17,590
Liabilities [Abstract]
Liability for Future Policy Benefits	176,005	166,701
Other Policy-Related Balances	15,026	13,030
Other Liabilities	26,745	$ 23,700
Assumed Reinsurance [Member] | Affiliated Entity [Member]
Assets [Abstract]
Premiums, reinsurance and other receivables relating to variable interest entities	162
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	393
Reinsurance Assets	555
Liabilities [Abstract]
Liability for Future Policy Benefits	1,666
Other Policy-Related Balances	121
Other Liabilities	1,460
Reinsurance Liabilities	3,247
Ceded Reinsurance [Member] | Affiliated Entity [Member]
Assets [Abstract]
Premiums, reinsurance and other receivables relating to variable interest entities	1,786
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	(22)
Reinsurance Assets	1,764
Liabilities [Abstract]
Liability for Future Policy Benefits	0
Other Policy-Related Balances	29
Other Liabilities	22
Reinsurance Liabilities	$ 51