Investments (Net Investment Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net Investment Income [Line Items]
Less: Investment expenses	$ 296	$ 302
Subtotal	4,559	5,461
Securities Investment
Net Investment Income [Line Items]
Subtotal	4,949	5,082
Subtotal	4,653	4,780
Fixed maturity securities
Net Investment Income [Line Items]
Subtotal	3,654	3,541
Equity securities
Net Investment Income [Line Items]
Subtotal	37	31
Actively traded securities and FVO general account securities
Net Investment Income [Line Items]
Subtotal	6	37
Changes in estimated fair value included in net investment income	5	6
Mortgage loans
Net Investment Income [Line Items]
Subtotal	807	730
Policy loans
Net Investment Income [Line Items]
Subtotal	149	152
Real estate and real estate joint ventures
Net Investment Income [Line Items]
Subtotal	157	211
Other limited partnership interests
Net Investment Income [Line Items]
Subtotal	46	215
Cash, cash equivalents and short-term investments
Net Investment Income [Line Items]
Subtotal	40	35
Operating joint ventures
Net Investment Income [Line Items]
Subtotal	12	8
Other
Net Investment Income [Line Items]
Subtotal	41	122
Consolidated Securitization Entities And Fair Value Option Contractholder-Directed Unit-Linked
Net Investment Income [Line Items]
Subtotal	(94)	681
FVO contractholder-directed unit-linked investments
Net Investment Income [Line Items]
Subtotal	(97)	677
Changes in estimated fair value included in net investment income	(191)	536
Commercial mortgage loans | Consolidated Securitization Entities
Net Investment Income [Line Items]
Subtotal	$ 3	$ 4