Income Taxes (Tables)

6 Months Ended

Jun. 30, 2021

Income Tax Disclosure [Abstract]

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

	For the Three Months Ended June 30,														For the Six Months Ended June 30,
	2021							2020							2021							2020
(in thousands)	Amount			%				Amount			%				Amount			%				Amount			%
Provision for income taxes at the statutory rate of 21%	$	21,424			21.0		%	$	24,124			21.0		%	$	40,290			21.0		%	$	7,458			21.0		%
Increase (reduction) in taxes resulting from:
Excess tax benefit on share-based compensation		(270	)		(0.3	)	%		(265	)		(0.2	)	%		(2,194	)		(1.1	)	%		(1,293	)		(3.6	)	%
Tax exempt interest income		(310	)		(0.3	)	%		(323	)		(0.3	)	%		(629	)		(0.3	)	%		(636	)		(1.8	)	%
Dividends received deduction		(248	)		(0.2	)	%		(212	)		(0.2	)	%		(484	)		(0.3	)	%		(484	)		(1.4	)	%
Investment tax credit		(801	)		(0.8	)	%		(129	)		(0.1	)	%		(1,603	)		(0.8	)	%		(1,449	)		(4.0	)	%
ESOP dividends paid deduction		(137	)		(0.1	)	%		(137	)		(0.1	)	%		(267	)		(0.1	)	%		(269	)		(0.8	)	%
Nondeductible expenses		826			0.8		%		161			0.1		%		1,237			0.6		%		364			1.0		%
Other items, net		(278	)		(0.3	)	%		(506	)		(0.4	)	%		678			0.3		%		925			2.6		%
Total tax expense	$	20,206			19.8		%	$	22,713			19.8		%	$	37,028			19.3		%	$	4,616			13.0		%