Fair value measurements Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2017		Sep. 30, 2016		Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Guaranteed Minimum Income Benefit [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Reported liabilities	$ 635		$ 1,200		$ 635		$ 1,200		$ 684	$ 853	$ 1,300	$ 888
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - Beginning of Period, Liabilities	357	[1]	971	[2]	559	[3]	609	[4]
Transfers into level 3, liability	0		0		9		0
Transfers out of Level 3, Liabilities	0		0		0		0
Change in Net Unrealized Gains (Losses) included in OCI, Liabilities	0		0		0		0
Net Realized Gains/Losses, Liabilities	(54)		(88)		(265)		274
Purchases, Liabilities	0		0		0		0	[4],[5]
Sales, Liabilities	0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	0		0		0		0
Balance - End of Period, Liabilities	303	[1],[3]	883	[2],[4]	303	[1],[3]	883	[2],[4]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(54)		(88)		(265)		274
Other Derivative Instruments Fair Value [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - Beginning of Period, Liabilities	2		10		13		6
Transfers into level 3, liability	0		0		0		0
Transfers out of Level 3, Liabilities	0		0		(9)		0
Change in Net Unrealized Gains (Losses) included in OCI, Liabilities	0		0		0		0
Net Realized Gains/Losses, Liabilities	0		0		(2)		2
Purchases, Liabilities	0		0		0		2	[4],[5]
Sales, Liabilities	0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	0		(2)		0		(2)
Balance - End of Period, Liabilities	2		8		2		8
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 0		$ 0		$ (2)		$ 2

[1] Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $635 million at September 30, 2017, and $684 million at June 30, 2017, which includes a fair value derivative adjustment of $303 million and $357 million, respectively.

[2] Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $1.2 billion at September 30, 2016, and $1.3 billion at June 30, 2016, which includes a fair value derivative adjustment of $883 million and $971 million, respectively.

[3] Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $635 million at September 30, 2017, and $853 million at December 31, 2016, which includes a fair value derivative adjustment of $303 million and $559 million, respectively

[4] Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $1.2 billion at September 30, 2016, and $888 million at December 31, 2015, which includes a fair value derivative adjustment of $883 million and $609 million, respectively.

[5] Includes acquired invested assets as a result of the Chubb Corp acquisition.