Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Schedule of Deferred Tax Assets and Deferred Tax Liabilities

(in thousands)	2022		2021
Deferred tax assets:
Tax discounting of unpaid losses and settlement expenses	$	23,788	$	22,637
Unearned premium offset		27,158		23,080
Net unrealized depreciation of securities		19,839		—
Deferred compensation		4,058		3,469
Share-based compensation expense		3,202		3,089
Capitalized research and development costs		2,544		—
Lease liability		3,026		3,796
Other		938		367
Deferred tax assets before allowance	$	84,553	$	56,438
Less valuation allowance		—		—
Total deferred tax assets	$	84,553	$	56,438
Deferred tax liabilities:
Net unrealized appreciation of securities	$	—	$	76,533
Deferred policy acquisition costs		26,850		21,746
Lease asset		2,681		3,101
Discounting of unpaid losses and settlement expenses - Tax Cuts and Jobs Act (TCJA) implementation offset		1,909		2,545
Fixed assets		3,083		3,518
Intangible assets		1,543		1,537
Undistributed earnings of unconsolidated investees		7,399		29,515
Other		819		1,452
Total deferred tax liabilities	$	44,284	$	139,947
Net deferred tax asset (liability)	$	40,269	$	(83,509)

Schedule of Reconciliation of Income Tax Expense Attributable to Income from Operations with Amounts Computed by Applying U.S. Federal Tax Rate to Pretax Income from Continuing Operations

(in thousands)	2022					2021					2020
Provision for income taxes at the statutory federal tax rates	$	151,342		21.0	%	$	72,307		21.0	%	$	39,867		21.0	%
Increase (reduction) in taxes resulting from:
Excess tax benefit on share-based compensation		(4,491)		(0.6)	%		(3,090)		(0.9)	%		(3,537)		(1.8)	%
Tax-exempt interest income		(1,143)		(0.2)	%		(1,219)		(0.3)	%		(1,293)		(0.7)	%
Dividends received deduction		(912)		(0.1)	%		(891)		(0.3)	%		(883)		(0.5)	%
Investment tax credit		(5,053)		(0.7)	%		(3,491)		(1.0)	%		(2,435)		(1.3)	%
ESOP dividends paid deduction		(4,171)		(0.6)	%		(1,566)		(0.5)	%		(1,083)		(0.6)	%
Unconsolidated investee dividends		—		—	%		—		—	%		(479)		(0.2)	%
Nondeductible expenses		1,263		0.2	%		3,834		1.1	%		1,878		1.0	%
Other items, net		432		0.0	%		(917)		(0.2)	%		715		0.4	%
Total	$	137,267	​	19.0	%	$	64,967	​	18.9	%	$	32,750	​	17.3	%