Income Taxes, Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Insurance reserves [Abstract]
Property and casualty claim and claim adjustment expense reserves		$ 157	$ 129
Unearned premium reserves		174	153
Receivables		11	11
Employee benefits		197	212
Deferred retroactive reinsurance benefit		83	82
Net operating loss carryforwards		13	275
Tax credit carryforwards		11	47
Basis differential in investment in subsidiary		8	8
Disallowed interest deduction			41
Other		189	179
Total deferred tax assets		843	1,137
Valuation allowance		(13)	(187)
Net deferred tax assets		830	950
Deferred tax liabilities [Abstract]
Deferred acquisition costs		(93)	(83)
Net unrealized gains		(441)	(263)
Property, plant and equipment		(721)	(848)
Basis differential in investment in subsidiary		(432)	(679)
Other liabilities		(165)	(208)
Total deferred tax liabilities		(1,852)	(2,081)
Net deferred tax liabilities	[1]	(1,022)	(1,131)
Other Assets [Member]
Insurance reserves [Abstract]
Total deferred tax assets		$ 43	$ 37

[1] Includes $43 and $37 of deferred tax assets reflected in Other assets in the Consolidated Balance Sheets at December 31, 2020 and 2019.