Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Schedule of Goodwill and Intangible Assets

	March 31,		December 31,
(in thousands)	2022		2021
Goodwill
Surety	$	40,816	$	40,816
Casualty		5,246		5,246
Total goodwill	$	46,062	$	46,062
Intangibles
Indefinite-lived intangibles - state insurance licenses		7,500		7,500
Total goodwill and intangibles	$	53,562	$	53,562

Schedule of Reconciliation of Numerator and Denominator of the Basic and Diluted Earnings Per Share Computations

	For the Three Months						For the Three Months
	Ended March 31, 2022						Ended March 31, 2021
	Income		Shares		Per Share		Income		Shares		Per Share
(in thousands, except per share data)	(Numerator)		(Denominator)		Amount		(Numerator)		(Denominator)		Amount
Basic EPS
Earnings available to common shareholders	$	47,923		45,306	$	1.06	$	73,012		45,178	$	1.62
Effect of Dilutive Securities
Stock options and restricted stock units		—		408				—		496
Diluted EPS
Earnings available to common shareholders	$	47,923		45,714	$	1.05	$	73,012		45,674	$	1.60
Anti-dilutive options excluded from diluted EPS				214						—

Schedule of Changes in the Balance of Each Component of Accumulated Other Comprehensive Earnings (Loss)

(in thousands)	For the Three Months
	Ended March 31,
Unrealized Gains/Losses on Available-for-Sale Securities	2022			2021
Beginning balance	$	49,826		$	108,714
Other comprehensive earnings (loss) before reclassifications		(115,742	)		(43,795	)
Amounts reclassified from accumulated other comprehensive earnings		161			(952	)
Net current-period other comprehensive earnings (loss)	$	(115,581	)	$	(44,747	)
Ending balance	$	(65,755	)	$	63,967
Balance of securities for which an allowance for credit losses has been recognized in net earnings	$	607		$	463

Schedule of Effects of Reclassifications out of Accumulated Other Comprehensive Earnings (Loss)

	Amount Reclassified from Accumulated Other
(in thousands)	Comprehensive Earnings (Loss)
	For the Three Months
Component of Accumulated	Ended March 31,						Affected line item in the
Other Comprehensive Earnings (Loss)	2022			2021			Statement of Earnings
Unrealized gains and losses on available-for-sale securities	$	(51	)	$	1,183		Net realized gains (losses)
		(153	)		22		Credit gains (losses) presented within net realized gains
	$	(204	)	$	1,205		Earnings (loss) before income taxes
		43			(253	)	Income tax (expense) benefit
	$	(161	)	$	952		Net earnings (loss)