Investments - OTTI losses included in AOCI at the time of impairment for fixed income securities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Investments [Abstract]
Net unrealized gains related to changes in valuation of fixed income securities subsequent to impairment measurement date	$ 178	$ 180
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(85)	(86)
Municipal
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(5)	(5)
Corporate
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(3)	(2)
Asset-backed securities (“ABS”)
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(11)	(10)
Residential mortgage-backed securities (“RMBS”)
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(64)	(67)
Commercial mortgage-backed securities (“CMBS”)
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	$ (2)	$ (2)