Income Taxes - Significant components of deferred tax assets and liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Federal net operating loss carryforwards	$ 15	$ 19
Foreign underwriting losses	6	118
Capital loss carryforwards	7	0
Insurance claims and reserves	840	875
Employee benefits	104	93
Other, net	48	43
Total deferred tax assets before valuation allowance	1,020	1,148
Valuation allowance against deferred tax assets	(29)	(140)
Total deferred tax assets	991	1,008
Deferred tax liabilities:
Investment securities	(763)	(556)
Deferred policy acquisition costs	(71)	(150)
Insurance claims and reserves transition liability	(77)	(93)
Real estate, property and equipment	(37)	(35)
Total deferred tax liabilities	(948)	(834)
Net deferred tax asset (liability)	43	174
Excluding Unrealized Gains
Deferred tax assets:
Federal net operating loss carryforwards	15	19
Foreign underwriting losses	6	118
Capital loss carryforwards	7	0
Insurance claims and reserves	772	829
Employee benefits	104	93
Other, net	50	45
Total deferred tax assets before valuation allowance	954	1,104
Valuation allowance against deferred tax assets	(29)	(140)
Total deferred tax assets	925	964
Deferred tax liabilities:
Investment securities	(167)	(140)
Deferred policy acquisition costs	(267)	(293)
Insurance claims and reserves transition liability	(77)	(93)
Real estate, property and equipment	(37)	(35)
Total deferred tax liabilities	(548)	(561)
Net deferred tax asset (liability)	377	403
Impact of Unrealized Gains
Deferred tax assets:
Federal net operating loss carryforwards	0	0
Foreign underwriting losses	0	0
Capital loss carryforwards	0	0
Insurance claims and reserves	68	46
Employee benefits	0	0
Other, net	(2)	(2)
Total deferred tax assets before valuation allowance	66	44
Valuation allowance against deferred tax assets	0	0
Total deferred tax assets	66	44
Deferred tax liabilities:
Investment securities	(596)	(416)
Deferred policy acquisition costs, impact of unrealized gains	(196)	(143)
Insurance claims and reserves transition liability	0	0
Real estate, property and equipment	0	0
Total deferred tax liabilities	(400)	(273)
Net deferred tax asset (liability)	$ (334)	$ (229)