Investments - Other-than-temporary impairment losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	$ (7)	$ (46)	$ (120)
OTTI losses reclassified to (from) other comprehensive income	(2)	1	7
Net OTTI losses recognized in earnings	(9)	(45)	(113)
Municipal
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(1)	0
OTTI losses reclassified to (from) other comprehensive income	0	0	0
Net OTTI losses recognized in earnings	0	(1)	0
Corporate
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(1)	(7)	(23)
OTTI losses reclassified to (from) other comprehensive income	0	3	6
Net OTTI losses recognized in earnings	(1)	(4)	(17)
ABS
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(1)	(4)
OTTI losses reclassified to (from) other comprehensive income	(1)	(1)	0
Net OTTI losses recognized in earnings	(1)	(2)	(4)
RMBS
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(1)	0	0
OTTI losses reclassified to (from) other comprehensive income	0	(2)	(1)
Net OTTI losses recognized in earnings	(1)	(2)	(1)
CMBS
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(4)	(9)	(15)
OTTI losses reclassified to (from) other comprehensive income	(1)	1	2
Net OTTI losses recognized in earnings	(5)	(8)	(13)
Fixed income securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(6)	(18)	(42)
OTTI losses reclassified to (from) other comprehensive income	(2)	1	7
Net OTTI losses recognized in earnings	(8)	(17)	(35)
Mortgage loans
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(1)	0
OTTI losses reclassified to (from) other comprehensive income	0	0	0
Net OTTI losses recognized in earnings	0	(1)	0
Equity securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(16)	(59)
OTTI losses reclassified to (from) other comprehensive income	0	0	0
Net OTTI losses recognized in earnings	0	(16)	(59)
Limited partnership interests
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	0	(9)	(15)
OTTI losses reclassified to (from) other comprehensive income	0	0	0
Net OTTI losses recognized in earnings	0	(9)	(15)
Other
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment (“OTTI”) losses	(1)	(2)	(4)
OTTI losses reclassified to (from) other comprehensive income	0	0	0
Net OTTI losses recognized in earnings	$ (1)	$ (2)	$ (4)