Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Deferred tax asset:
Loss reserve discounting	$ 218,222	$ 230,956
Unearned premiums	216,721	200,938
Unrealized investment losses	58,701	126,693
Net operating losses & foreign tax credits	62,159	59,154
Other-than-temporary impairments	7,149	12,691
Employee compensation plans	70,529	68,062
Other	81,915	78,025
Gross deferred tax asset	715,396	776,519
Less valuation allowance	(36,063)	(36,283)
Deferred tax asset	679,333	740,236
Deferred tax liability:
Amortization of intangibles	15,124	15,205
Loss reserve discounting - transition rule	4,944	9,894
Deferred policy acquisition costs	195,150	176,281
Property, furniture and equipment	45,276	43,501
Investment funds	184,899	161,867
Other	78,874	66,525
Deferred tax liability	524,267	473,273
Net deferred tax asset	155,066	266,963
Operating Loss Carryforwards [Line Items]
Current federal income taxes	14,000	$ 46,000
Valuation allowance	36,000
Foreign Tax Jurisdiction
Deferred tax asset:
Net operating losses & foreign tax credits	23,000
Less valuation allowance	(13,000)
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, subject to expire	$ 196,000