Fair Value Measurements - Changes in balances of Level 3 financial liabilities carried at fair value (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial liabilities, Beginning Balance		$ (1,369)		$ (3,861)		$ (3,215)
Impact of accounting change				2,701
Total realized/unrealized gains (losses) included in Net income		(211)		(17)		(160)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)		0		0		0
Purchases and issuances		(277)		(257)		(1,038)
Sales and settlements		98		65		552
Transfer into Level 3		0		0		0
Transfer out of Level 3		0		0		0
Sale of subsidiaries				0
Financial liabilities, Ending Balance		(1,759)	[1]	(1,369)		(3,861)
Liabilities of MIE
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial liabilities, Beginning Balance		0		(2,701)		(2,411)
Impact of accounting change	[2]			2,701
Total realized/unrealized gains (losses) included in Net income				0		22	[3]
Total realized/unrealized gains (losses) included in other comprehensive income (loss)				0		0
Purchases and issuances				0		(817)
Sales and settlements				0		505
Transfer into Level 3				0		0
Transfer out of Level 3				0		0
Sale of subsidiaries				0
Financial liabilities, Ending Balance				0		(2,701)
Embedded derivatives
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial liabilities, Beginning Balance		(1,369)		(1,160)		(804)
Impact of accounting change				0
Total realized/unrealized gains (losses) included in Net income		(211)	[4]	(17)	[5]	(182)	[6]
Total realized/unrealized gains (losses) included in other comprehensive income (loss)		0		0		0
Purchases and issuances		(277)		(257)		(221)
Sales and settlements		98		65		47
Transfer into Level 3		0		0		0
Transfer out of Level 3		0		0		0
Sale of subsidiaries				0
Financial liabilities, Ending Balance		$ (1,759)		$ (1,369)		$ (1,160)

[1] As discussed above, these tables exclude the portion of MIE liabilities allocated to Level 3, which are derived from the fair value of the MIE assets.

[2] The impact of implementing new guidance adopted in 2015, as discussed above and in Note A — “Accounting Policies — Managed Investment Entities.”

[3] Total realized/unrealized gains (losses) included in net income includes gains of $50 million related to liabilities outstanding as of December 31, 2014. See Note H — “Managed Investment Entities.”

[4] Total realized/unrealized gains (losses) included in net income for the embedded derivatives reflects losses related to the unlocking of actuarial assumptions of $17 million in 2016.

[5] Total realized/unrealized gains (losses) included in net income for the embedded derivatives reflects losses related to the unlocking of actuarial assumptions of $28 million in 2015.

[6] Total realized/unrealized gains (losses) included in net income for the embedded derivatives reflects gains related to the unlocking of actuarial assumptions of $58 million in 2014.