Reinsurance (Effects of Affiliated Reinsurance on Earnings) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Premiums:
Reinsurance assumed	$ 1,673	$ 1,469	$ 1,350
Reinsurance ceded	(1,252)	(1,284)	(1,291)
Net premiums	21,384	20,475	19,880
Universal life and investment-type product policy fees:
Reinsurance assumed	48	41	39
Reinsurance ceded	(611)	(591)	(563)
Net universal life and investment-type product policy fees	2,466	2,363	2,239
Other revenues:
Reinsurance assumed	2	(2)	(6)
Reinsurance ceded	766	731	849
Other revenues	1,808	1,699	1,730
Policyholder benefits and claims:
Reinsurance assumed	1,416	1,225	1,208
Reinsurance ceded	(1,539)	(1,498)	(1,616)
Net policyholder benefits and claims	23,855	23,032	22,269
Interest credited to policyholder account balances:
Direct interest credited to policyholder account balances	2,227	2,322	2,455
Reinsurance assumed	35	35	33
Reinsurance ceded	(88)	(104)	(98)
Net interest credited to policyholder account balances	2,174	2,253	2,390
Other expenses:
Reinsurance assumed	399	427	479
Reinsurance ceded	540	533	587
Total other expenses	6,071	5,988	6,394
Affiliated Entity [Member]
Universal life and investment-type product policy fees:
Net universal life and investment-type product policy fees	129	127	108
Other revenues:
Other revenues	177	142	113
Affiliated Entity [Member] | Assumed Reinsurance [Member]
Premiums:
Reinsurance assumed	681	451	319
Universal life and investment-type product policy fees:
Reinsurance assumed	48	40	39
Other revenues:
Reinsurance assumed	2	(2)	(6)
Policyholder benefits and claims:
Reinsurance assumed	623	402	334
Interest credited to policyholder account balances:
Reinsurance assumed	33	31	30
Other expenses:
Reinsurance assumed	298	326	357
Affiliated Entity [Member] | Ceded Reinsurance [Member]
Premiums:
Reinsurance ceded	(36)	(45)	(54)
Universal life and investment-type product policy fees:
Reinsurance ceded	(240)	(221)	(216)
Other revenues:
Reinsurance ceded	713	675	790
Policyholder benefits and claims:
Reinsurance ceded	(197)	(144)	(177)
Interest credited to policyholder account balances:
Reinsurance ceded	(88)	(102)	(98)
Other expenses:
Reinsurance ceded	680	653	789
Affiliated Entity [Member] | Reinsurance [Member]
Premiums:
Net premiums	645	406	265
Universal life and investment-type product policy fees:
Net universal life and investment-type product policy fees	(192)	(181)	(177)
Other revenues:
Other revenues	715	673	784
Policyholder benefits and claims:
Net policyholder benefits and claims	426	258	157
Interest credited to policyholder account balances:
Net interest credited to policyholder account balances	(55)	(71)	(68)
Other expenses:
Total other expenses	$ 978	$ 979	$ 1,146