Reinsurance (Effects of Reinsurance on Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets:
Premiums, reinsurance and other receivables	$ 20,101	$ 22,251
Deferred policy acquisition costs and value of business acquired	5,274	4,809	$ 4,890
Total assets	25,375	27,060
Liabilities:
Future policy benefits	31,684	29,894
Policyholder Account Balances	35,587	35,661	$ 35,486
Other policy-related balances	3,384	3,549
Other Liabilities	10,147	7,682
Total liabilities	80,802	76,786
Direct
Assets:
Premiums, reinsurance and other receivables	1,143	630
Deferred policy acquisition costs and value of business acquired	6,020	5,467
Total assets	7,163	6,097
Liabilities:
Future policy benefits	31,567	28,670
Policyholder Account Balances	34,635	34,764
Other policy-related balances	1,027	990
Other Liabilities	4,466	2,566
Total liabilities	71,695	66,990
Assumed
Assets:
Premiums, reinsurance and other receivables	23	162
Deferred policy acquisition costs and value of business acquired	71	219
Total assets	94	381
Liabilities:
Future policy benefits	234	1,294
Policyholder Account Balances	952	897
Other policy-related balances	1,677	1,804
Other Liabilities	12	86
Total liabilities	2,875	4,081
Ceded
Assets:
Premiums, reinsurance and other receivables	18,935	21,459
Deferred policy acquisition costs and value of business acquired	(817)	(877)
Total assets	18,118	20,582
Liabilities:
Future policy benefits	(117)	(70)
Policyholder Account Balances	0	0
Other policy-related balances	680	755
Other Liabilities	5,669	5,030
Total liabilities	$ 6,232	$ 5,715