Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

Components of Income Tax Expense

(Dollar amounts in thousands)

	Years Ended December 31,
	2020		2019		2018
Current income tax expense (benefit):
Federal	$	29,310	$	50,141	$	13,497
State	6,829		5,116		(619)
Total	36,139		55,257		12,878
Deferred income tax (benefit) expense:
Federal	(6,183)		(1,879)		14,489
State	(2,873)		12,823		11,820
Total	(9,056)		10,944		26,309
Total income tax expense	$	27,083	$	66,201	$	39,187

Schedule of Effective Income Tax Rate Reconciliation

Components of Effective Tax Rate

(Dollar amounts in thousands)

	Years Ended December 31,
	2020				2019				2018
	Amount		% of Pretax Income		Amount		% of Pretax Income		Amount		% of Pretax Income
Statutory federal income tax	$	28,346	21.0		$	55,847	21.0		$	41,382	21.0
Increase (decrease) in income taxes resulting from:
State income tax, net of federal income tax effect	3,125		2.3	%	14,172		5.3		8,846		4.5
Tax-exempt income, net of interest expense   disallowance	(2,589)		(1.9)		(3,234)		(1.2)		(3,104)		(1.6)
Deferred tax asset revaluation	—		—		—		—		(8,721)		(4.4)
Other	(1,799)		(1.3)		(584)		(0.2)		784		0.4
Total	$	27,083	20.1	%	$	66,201	24.9	%	$	39,187	19.9	%

Schedule of Deferred Tax Assets and Liabilities

Deferred Tax Assets and Liabilities

(Dollar amounts in thousands)

	As of December 31,
	2020		2019
Deferred tax assets:
Allowance for credit losses	$	49,829	$	21,010
Lease Liability	32,233		33,871
Federal net operating loss ("NOL") carryforwards	17,128		21,489
Non-equity based compensation	5,111		7,115
Equity based compensation	4,890		5,043
OREO	1,053		1,996
Fixed assets	220		—
Alternative minimum tax ("AMT") and other credit carryforwards	—		368
State NOL carryforwards	83		—
Deferred loan fees	—		—
Other	14,263		6,988
Total deferred tax assets	124,810		97,880
Deferred tax liabilities:
Right-of-use asset	(26,308)		(29,611)
Acquisition adjustments	(11,549)		(1,261)
Accrued retirement benefits	(8,254)		(8,453)
Deferred loan fees and costs	(6,361)		(5,445)
Fixed assets	—		(5,648)
Other	(2,780)		(2,821)
Total deferred tax liabilities	(55,252)		(53,239)
Deferred tax valuation allowance	(2,132)		(1,984)
Net deferred tax assets	67,426		42,657
Tax effect of adjustments related to other comprehensive income (loss)	(10,048)		725
Net deferred tax assets including adjustments	$	57,378	$	43,382
NOL carryforwards available to offset future taxable income:
Federal gross NOL carryforwards, begin to expire in 2030	$	84,488	$	102,328
Illinois gross NOL carryforwards	1,143		—
AMT credits	—		204

Summary of Income Tax Contingencies

Rollforward of Unrecognized Tax Benefits

(Dollar amounts in thousands)

	Years Ended December 31,
	2020		2019		2018
Beginning balance	$	16,384	$	16,350	$	16,248
Additions for tax positions relating to the current year	793		1,158		1,209
Additions for tax positions relating to prior years	1,997		—		582
Reductions for tax positions relating to prior years	(876)		(224)		(60)
Reduction in lapse in statute of limitations	(781)		—		—
Reductions for settlements with taxing authorities	—		(900)		(1,629)
Ending balance	$	17,517	$	16,384	$	16,350
Interest and penalties not included above(1):
Interest expense (income), net of tax effect, and penalties	$	48	$	38	$	(21)
Accrued interest and penalties, net of tax effect, at end of year	256		208		170

(1)Included in income tax expense in the Consolidated Statements of Income.