Investments (Summary of Amortized Costs and Estimated Fair Values of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	$ 796,960	$ 1,508,981
Unrealized Gains	145	16,235
Unrealized Losses	(101,230)	(17,730)
Fair Value	695,875	1,507,486
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	49,678	112,086
Unrealized Gains	11	5,392
Unrealized Losses	(463)	0
Fair Value	49,226	117,478
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	598,845	1,003,869
Unrealized Gains	131	7,856
Unrealized Losses	(84,957)	(11,468)
Fair Value	514,019	1,000,257
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	122,760	361,781
Unrealized Gains	0	2,835
Unrealized Losses	(13,413)	(5,767)
Fair Value	109,347	358,849
Subordinated corporate bonds
Debt Securities, Available-for-sale [Abstract]
Amortized Cost	25,677	22,660
Unrealized Gains	3	152
Unrealized Losses	(2,397)	(254)
Fair Value	$ 23,283	22,558
Obligations of U.S. government-sponsored enterprises
Debt Securities, Available-for-sale [Abstract]
Amortized Cost		8,585
Unrealized Gains		0
Unrealized Losses		(241)
Fair Value		$ 8,344

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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