Investments - Other-than-temporary impairment losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	$ (24)	$ (7)	$ (46)
OTTI losses reclassified to (from) other comprehensive income	3	(2)	1
Net OTTI losses recognized in earnings	(21)	(9)	(45)
Net OTTI losses recognized in earnings			(45)
Municipal
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(2)	0	(1)
OTTI losses reclassified to (from) other comprehensive income	2	0	0
Net OTTI losses recognized in earnings	0	0
Net OTTI losses recognized in earnings			(1)
Corporate
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(1)	(1)	(7)
OTTI losses reclassified to (from) other comprehensive income	(1)	0	3
Net OTTI losses recognized in earnings	(2)	(1)
Net OTTI losses recognized in earnings			(4)
ABS
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(1)	0	(1)
OTTI losses reclassified to (from) other comprehensive income	0	(1)	(1)
Net OTTI losses recognized in earnings	(1)	(1)
Net OTTI losses recognized in earnings			(2)
MBS
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(4)	(5)	(9)
OTTI losses reclassified to (from) other comprehensive income	2	(1)	(1)
Net OTTI losses recognized in earnings	(2)	(6)
Net OTTI losses recognized in earnings			(10)
Fixed income securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(8)	(6)	(18)
OTTI losses reclassified to (from) other comprehensive income	3	(2)	1
Net OTTI losses recognized in earnings	(5)	(8)
Net OTTI losses recognized in earnings			(17)
Mortgage loans
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	0	(1)
OTTI losses reclassified to (from) other comprehensive income	0	0	0
Net OTTI losses recognized in earnings	0	0
Net OTTI losses recognized in earnings			(1)
Equity securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	0	(16)
OTTI losses reclassified to (from) other comprehensive income	0	0	0
Net OTTI losses recognized in earnings	0	0
Net OTTI losses recognized in earnings			(16)
Limited partnership interests
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(2)	0	(9)
OTTI losses reclassified to (from) other comprehensive income	0	0	0
Net OTTI losses recognized in earnings	(2)	0
Net OTTI losses recognized in earnings			(9)
Other
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(14)	(1)	(2)
OTTI losses reclassified to (from) other comprehensive income	0	0	0
Net OTTI losses recognized in earnings	$ (14)	$ (1)
Net OTTI losses recognized in earnings			$ (2)