CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
REVENUES:
Premiums earned	$ 8,536	$ 7,876	$ 7,179
Net investment income	993	638	745
Total net gains (losses) on investments	(180)	(982)	501
Other income (expense)	(11)	(6)	23
Total revenues	9,337	7,526	8,448
CLAIMS AND EXPENSES:
Incurred losses and loss adjustment expenses	5,578	5,823	5,387
Commission, brokerage, taxes and fees	1,851	1,632	1,513
Other underwriting expenses	574	501	454
Corporate expenses	18	26	33
Interest, fee and bond issue cost amortization expense	134	101	70
Total claims and expenses	8,156	8,083	7,457
INCOME (LOSS) BEFORE TAXES	1,181	(557)	991
Income tax expense (benefit)	210	(112)	192
NET INCOME (LOSS)	972	(445)	800
Other comprehensive income (loss), net of tax:
Unrealized appreciation (depreciation) ("URA(D)") on securities arising during the period	374	(1,011)	(200)
Reclassification adjustment for realized losses (gains) included in net income (loss)	153	73	9
Total URA(D) on securities arising during the period	527	(938)	(191)
Foreign currency translation adjustments	17	(18)	(9)
Benefit plan actuarial net gain (loss) for the period	15	15	17
Reclassification adjustment for amortization of net (gain) loss included in net income (loss)	2	2	6
Total benefit plan net gain (loss) for the period	17	17	23
Total other comprehensive income (loss), net of tax	561	(939)	(177)
COMPREHENSIVE INCOME (LOSS)	$ 1,533	$ (1,384)	$ 623