Investments - Carrying Amount and Fair Values of Available for Sale Securities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fixed maturity investments available for sale:
Carrying Value, debt securities	$ 2,090	$ 1,998
Cost Basis	2,029	2,009
Unrealized Gains	67	9
Unrealized Losses	(6)	(20)
U.S. government and agencies
Fixed maturity investments available for sale:
Carrying Value, debt securities	288	225
Cost Basis	282	226
Unrealized Gains	7	1
Unrealized Losses	(1)	(2)
States and political subdivisions
Fixed maturity investments available for sale:
Carrying Value, debt securities	93	148
Cost Basis	90	147
Unrealized Gains	3	1
Unrealized Losses	0	0
Corporate debt securities
Fixed maturity investments available for sale:
Carrying Value, debt securities	1,587	1,503
Cost Basis	1,536	1,510
Unrealized Gains	54	6
Unrealized Losses	(3)	(13)
Foreign government bonds
Fixed maturity investments available for sale:
Carrying Value, debt securities	60	62
Cost Basis	61	67
Unrealized Gains	1	0
Unrealized Losses	(2)	(5)
Mortgage-backed/asset-backed securities
Fixed maturity investments available for sale:
Carrying Value, debt securities	62	60
Cost Basis	60	59
Unrealized Gains	2	1
Unrealized Losses	$ 0	$ 0

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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