Investments - Other-than-temporary impairment losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	$ (6)	$ (2)	$ (13)	$ (2)
Included in OCI	1	0	1	(1)
Net OTTI losses recognized in earnings	(5)	(2)	(12)	(3)
Corporate
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	(1)	0	(1)	0
Included in OCI	(1)	0	(1)	0
Net OTTI losses recognized in earnings	(2)	0	(2)	0
ABS
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	(1)	0	(1)	0
Included in OCI	0	0	0	0
Net OTTI losses recognized in earnings	(1)	0	(1)	0
RMBS
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	0	(1)	0	(1)
Included in OCI	0	0	0	0
Net OTTI losses recognized in earnings	0	(1)	0	(1)
CMBS
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	(2)	0	(2)	0
Included in OCI	2	0	2	(1)
Net OTTI losses recognized in earnings	0	0	0	(1)
Fixed income securities
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	(4)	(1)	(4)	(1)
Included in OCI	1	0	1	(1)
Net OTTI losses recognized in earnings	(3)	(1)	(3)	(2)
Limited partnership interests
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	(1)	0	(2)	0
Included in OCI	0	0	0	0
Net OTTI losses recognized in earnings	(1)	0	(2)	0
Other
OTTI losses
Total other-than-temporary impairment (“OTTI”) losses	(1)	(1)	(7)	(1)
Included in OCI	0	0	0	0
Net OTTI losses recognized in earnings	$ (1)	$ (1)	$ (7)	$ (1)