Segment information Segment Information (narrative Detail (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Gain (Loss) on Derivative	$ (223)	$ (17)	$ (562)	$ 91
Net investment income	873	823	2,568	2,457
North America Agricultural Insurance [Member]
Segment Reporting Information [Line Items]
Segment Income Loss Including Gains Losses On Crop Derivatives	1
Gain (Loss) on Derivative	14
Net investment income	8	7	22	20
Segment Life [Member]
Segment Reporting Information [Line Items]
Net investment income	92	$ 85	$ 278	$ 253
Management Underwriting Income (Loss)	79
Gains(Losses) On Fair Value Changes In Separate Account Assets	$ 7