Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Summary of Differences in Taxes from Continuing Operations Computed at Statutory Rate

Following is a summary of the major items comprising the differences in taxes from continuing operations computed at the federal statutory rate and as recorded in the consolidated statement of income:

	Years Ended December 31,
(dollars in thousands)	2020			2019			2018
Provision at statutory rate of 21%	$	53,667		$	60,975		$	43,823
Tax-exempt income:
Tax-exempt interest	(10,776)			(10,243)			(9,021)
Section 291/265 interest disallowance	189			435			321
Company-owned life insurance income	(2,290)			(2,423)			(2,223)
Tax-exempt income	(12,877)			(12,231)			(10,923)
State income taxes	4,840			6,720			5,621
Tax credit investments - federal	(15,159)			(4,411)			(21,576)
Other, net	(1,324)			1,097			905
Income tax expense	$	29,147		$	52,150		$	17,850
Effective tax rate	11.4		%	18.0		%	8.6		%

Provision for Income Taxes

The provision for income taxes consisted of the following components:

	Years Ended December 31,
(dollars in thousands)	2020		2019		2018
Income taxes currently payable:
Federal	$	19,223	$	22,908	$	12,256
State	6,498		4,490		4,601
Deferred income taxes related to:
Federal	3,188		20,402		(1,513)
State	238		4,350		2,506
Deferred income tax expense	3,426		24,752		993
Income tax expense	$	29,147	$	52,150	$	17,850

Schedule of Significant Components of Net Deferred Tax Assets (Liabilities)

Significant components of net deferred tax assets (liabilities) were as follows:

	December 31,
(dollars in thousands)	2020		2019
Deferred Tax Assets
Allowance for loan losses, net of recapture	$	34,971	$	14,179
Benefit plan accruals	20,076		19,673
Alternative minimum tax credit	—		1,272
Net operating loss carryforwards	18,982		25,336
Deferred gain on securities	2,102		3,754
Acquired loans	11,989		16,784
Operating lease liabilities	24,245		26,503
Tax credit investments and other partnerships	1,054		1,765
Other real estate owned	28		141
Other, net	460		591
Total deferred tax assets	113,907		109,998
Deferred Tax Liabilities
Purchase accounting	(18,232)		(17,564)
Loan servicing rights	(6,582)		(6,289)
Premises and equipment	(14,008)		(12,167)
Prepaid expenses	(955)		(973)
Operating lease right-of-use assets	(21,569)		(25,448)
Unrealized gains on available-for-sale investment securities	(40,756)		(15,751)
Unrealized gains on hedges	(1,080)		(78)
Other, net	(1,555)		(2,023)
Total deferred tax liabilities	(104,737)		(80,293)
Net deferred tax assets	$	9,170	$	29,705