Fair value measurements Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation (Details) - Guaranteed Minimum Income Benefit [Member] - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019		Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Guaranteed Benefit Liability, Net		$ 1,372		$ 815		$ 1,372		$ 815		$ 1,591	$ 897	$ 741	$ 861
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - Beginning of Period, Liabilities		1,141		338		456		452
Balance - End of Period, Liabilities		928		403		928		403
Guarantees [Member] | Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - Beginning of Period, Liabilities		1,141	[1]	338	[2]	456		452	[2]
Transfers into level 3, liability				0		0		0
Transfers out of Level 3, Liabilities		0				0		0
Change in Net Unrealized Gains (Losses) included in OCI, Liabilities		0		0		0		0
Net Realized Gains/Losses, Liabilities		(213)	[1]	65	[2]	472		(49)	[2]
Purchases, Liabilities		0		0		0		0
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	[2]	928	[1]	403		928	[1]	403
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)		$ (213)	[1]	$ 65	[2]	$ 472		$ (49)	[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 $1,372 million at June 30, 2020, and $1,591 million at March 31, 2020, which includes a fair value derivative adjustment of $928 million and $1,141 million, respectivel

[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 $815 million at June 30, 2019, and $741 million at March 31, 2019, which includes a fair value derivative adjustment of $403 million and $338 million, respectively