Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax asset:
Loss reserve discounting	$ 192,181	$ 162,636
Unearned premiums	180,326	163,143
Unrealized investment losses	228,456	0
Net operating losses & foreign tax credits	58,182	88,502
Other-than-temporary impairments	5,935	5,176
Employee compensation plans	63,313	61,301
Other	72,536	54,269
Gross deferred tax asset	800,929	535,027
Less valuation allowance	(47,166)	(75,230)
Deferred tax asset	753,763	459,797
Deferred tax liability:
Amortization of intangibles	13,973	12,787
Loss reserve discounting - transition rule	14,843	19,796
Deferred policy acquisition costs	157,055	137,893
Unrealized investment gains	0	36,850
Property, furniture and equipment	45,887	43,186
Investment funds	125,525	101,999
Other	67,479	67,331
Deferred tax liability	424,762	419,842
Net deferred tax asset	329,001	39,955
Operating Loss Carryforwards [Line Items]
Income taxes receivable	5,000
Current federal income taxes		3,000
Valuation allowance	47,000	$ 75,000
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, subject to expire	4,000
Operating loss carryforwards, not subject to expire	$ 225,000