Related Party Transactions (Effects of Affiliated Reinsurance on Balance Sheets) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Assets:
Assets	$ 207,226	$ 212,045
Premiums, reinsurance and other receivables	12,990	12,918
Deferred policy acquisition costs and value of business acquired	5,457	5,623
Liabilities:
Liabilities	191,163	195,177
Future policy benefits	35,327	35,715
Policyholder account balances	37,186	37,069
Other Liabilities	4,361	4,419
Assumed
Assets:
Premiums, reinsurance and other receivables	43	34
Liabilities:
Policyholder account balances	370	436
Other policy-related balances	1,682	1,683
Other Liabilities	(7)	(8)
Ceded
Assets:
Premiums, reinsurance and other receivables	3,286	3,254
Liabilities:
Policyholder account balances	0	0
Other policy-related balances	0	0
Other Liabilities	$ 374	$ 401