Income Taxes - Significant components of deferred tax assets and liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Federal net operating loss carryforwards	$ 19	$ 23
Foreign underwriting losses	118	93
Insurance claims and reserves	875	743
Employee benefits	93	88
Other, net	43	44
Total deferred tax assets before valuation allowance	1,148	991
Valuation allowance against deferred tax assets	(140)	(119)
Total deferred tax assets	1,008	872
Deferred tax liabilities:
Investment securities	(556)	(70)
Deferred policy acquisition costs	(150)	(291)
Insurance claims and reserves transition liability	(93)	(110)
Real estate, property and equipment	(35)	(36)
Total deferred tax liabilities	(834)	(507)
Net deferred tax asset (liability)	174	365
Excluding Unrealized Gains
Deferred tax assets:
Federal net operating loss carryforwards	19	23
Foreign underwriting losses	118	93
Insurance claims and reserves	829	740
Employee benefits	93	88
Other, net	45	44
Total deferred tax assets before valuation allowance	1,104	988
Valuation allowance against deferred tax assets	(140)	(119)
Total deferred tax assets	964	869
Deferred tax liabilities:
Investment securities	(140)	(36)
Deferred policy acquisition costs	(293)	(300)
Insurance claims and reserves transition liability	(93)	(110)
Real estate, property and equipment	(35)	(36)
Total deferred tax liabilities	(561)	(482)
Net deferred tax asset (liability)	403	387
Impact of Unrealized Gains
Deferred tax assets:
Federal net operating loss carryforwards	0	0
Foreign underwriting losses	0	0
Insurance claims and reserves	46	3
Employee benefits	0	0
Other, net	(2)	0
Total deferred tax assets before valuation allowance	44	3
Valuation allowance against deferred tax assets	0	0
Total deferred tax assets	44	3
Deferred tax liabilities:
Investment securities	(416)	(34)
Deferred policy acquisition costs	143	9
Insurance claims and reserves transition liability	0	0
Real estate, property and equipment	0	0
Total deferred tax liabilities	(273)	(25)
Net deferred tax asset (liability)	$ (229)	$ (22)