Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues
Property and casualty insurance premiums (net of reinsurance ceded and indemnification programs of $1,141, $1,122 and $1,016)	$ 39,517	$ 38,577	$ 36,513
Net investment income	2,853	3,159	3,240
Realized capital gains (losses)	1,356	1,885	(877)
Total revenues	44,791	44,675	39,815
Costs and expenses
Property and casualty insurance claims and claims expense (net of reinsurance ceded and indemnification programs of $530, $524 and $1,378)	22,001	23,976	22,778
Shelter-in-Place Payback expense	948	0	0
Life contract benefits (net of reinsurance ceded of $155, $165 and $240)	2,243	2,039	1,973
Interest credited to contractholder funds (net of reinsurance ceded of $27, $20 and $24)	638	640	654
Amortization of deferred policy acquisition costs	5,630	5,533	5,222
Operating costs and expenses	5,732	5,690	5,594
Pension and other postretirement remeasurement (gains) losses	(51)	114	468
Restructuring and related charges	259	41	67
Amortization of purchased intangibles	118	126	105
Impairment of purchased intangibles	0	106	0
Interest expense	318	327	332
Total costs and expenses	37,836	38,592	37,193
Gain on disposition of operations	4	6	6
Income from operations before income tax expense	6,959	6,089	2,628
Income tax expense	1,383	1,242	468
Net income	5,576	4,847	2,160
Preferred stock dividends	115	169	148
Net income applicable to common shareholders	$ 5,461	$ 4,678	$ 2,012
Earnings per common share:
Net income applicable to common shareholders earnings per common share - Basic (in dollars per share)	$ 17.53	$ 14.25	$ 5.78
Weighted average common shares - Basic (in shares)	311.6	328.2	347.8
Net income applicable to common shareholders earnings per common share - Diluted (in dollars per share)	$ 17.31	$ 14.03	$ 5.70
Weighted average common shares - Diluted (in shares)	315.5	333.5	353.2
Property and casualty insurance premiums
Revenues
Property and casualty insurance premiums (net of reinsurance ceded and indemnification programs of $1,141, $1,122 and $1,016)	$ 37,073	$ 36,076	$ 34,048
Life insurance
Revenues
Property and casualty insurance premiums (net of reinsurance ceded and indemnification programs of $1,141, $1,122 and $1,016)	1,516	1,512	1,482
Insurance premiums, commissions and fees	2,444	2,501	2,465
Other revenue
Revenues
Insurance premiums, commissions and fees	$ 1,065	$ 1,054	$ 939