Reinsurance (Effects of Reinsurance on Earnings) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Premiums:
Direct premiums	$ 2,117	$ 2,281	$ 2,226
Reinsurance assumed	79	297	94
Reinsurance ceded	(1,275)	(1,145)	(1,168)
Net premiums	921	1,433	1,152
Universal life and investment-type product policy fees:
Direct universal life and investment-type product policy fees	3,476	3,607	3,610
Reinsurance assumed	129	142	398
Reinsurance ceded	(909)	(809)	(815)
Net universal life and investment-type product policy fees	2,696	2,940	3,193
Other revenues:
Direct other revenues	259	258	259
Reinsurance assumed	87	0	28
Reinsurance ceded	415	246	252
Net other revenues	761	504	539
Policyholder benefits and claims:
Direct policyholder benefits and claims	5,909	4,807	4,797
Reinsurance assumed	128	305	263
Reinsurance ceded	(3,053)	(2,416)	(2,296)
Net policyholder benefits and claims	2,984	2,696	2,764
Interest credited to policyholder account balances:
Direct interest credited to policyholder account balances	1,027	1,104	1,125
Reinsurance assumed	75	78	76
Reinsurance ceded	145	145	139
Net interest credited to policyholder account balances	957	1,037	1,062
Amortization of deferred policy acquisition costs and value of business acquired
Direct amortization of deferred policy acquisition costs and value of business acquired	(114)	630	958
Reinsurance assumed	148	8	100
Reinsurance ceded	(206)	(43)	(68)
Direct amortization of deferred policy acquisition costs and value of business acquired	(172)	595	990
Other expenses:
Direct other expenses	1,482	1,512	1,566
Reinsurance assumed	35	47	6
Reinsurance ceded	221	163	192
Total other expenses	$ 1,738	$ 1,722	$ 1,764