Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Schedule of Income Tax Expense

Income tax expense consists of the following:

Year ended December 31,	2022		2021		2020
Current:
Federal	$	45.2	$	39.4	$	42.4
State	14.4		11.3		12.3
Total current	59.6		50.7		54.7
Deferred:
Federal	(3.7)		3.7		(5.7)
State	(1.0)		1.3		(0.9)
Total deferred	(4.7)		5.0		(6.6)
Total income tax expense	$	54.9	$	55.7	$	48.1

Schedule of Effective Income Tax Rate Reconciliation

Total income tax provision differs from the amount of income tax determined by applying the statutory federal income tax rate of 21% for the periods presented to income before income taxes due to the following:

Year ended December 31,	2022		2021		2020
Tax expense at the statutory tax rate	$	54.0	$	52.0	$	44.0
Increase (decrease) in tax resulting from:
Tax-exempt income	(8.4)		(2.8)		(2.1)
State income tax, net of federal income tax benefit	10.6		9.9		9.0
Deficiency (benefit) of stock-based compensation plans	0.2		(0.5)		(0.4)
Nondeductible transaction costs	2.0		0.8		—
Federal tax credits	(4.3)		(4.3)		(2.3)
Other, net	0.8		0.6		(0.1)
Tax expense at effective tax rate	$	54.9	$	55.7	$	48.1

Schedule of Deferred Tax Assets and Liabilities

The tax effects of temporary differences between the financial statement carrying amounts and tax bases of assets and liabilities that give rise to significant portions of the net deferred tax asset (liability) relate to the following:

December 31,	2022		2021
Deferred tax assets:
Loans, principally due to allowance for credit losses	$	54.8	$	30.7
Loan discount	32.5		1.6
Investment securities, unrealized losses	157.9		4.6
Derivatives, unrealized losses	0.5		—
Deferred compensation	26.8		19.3
Non-performing loan interest	2.6		1.0
Other real estate owned write-downs and carrying costs	1.5		—
Net operating loss carryforwards (1)	1.5		1.7
Lease liabilities	12.0		8.7
Other reserves	8.8		—
Contract incentives	8.5		—
Discount on acquired investment securities	13.4		—
Other	2.4		3.5
Deferred tax assets	$	323.2	$	71.1

December 31,	2022		2021
Deferred tax liabilities:
Fixed assets, principally differences in bases and depreciation	$	(17.3)	$	(7.7)
Deferred loan costs	(3.3)		(1.9)
Derivatives, unrealized gains	—		(1.0)
Investment in joint venture partnership, principally due to differences in depreciation of partnership assets	(1.3)		(0.9)
Right of use assets	(11.3)		(8.3)
Prepaid amounts	(0.9)		(0.7)
Government agency stock dividends	(1.2)		(1.2)
Goodwill and other intangibles	(68.2)		(51.2)
Mortgage servicing rights	(7.4)		(6.8)
Other	(1.8)		(0.7)
Deferred tax liabilities	(112.7)		(80.4)
Net deferred tax assets (liabilities)	$	210.5	$	(9.3)

(1) As of December 31, 2022, we had remaining federal net operating loss carryforwards of $2.7 million from acquired companies, which is available to offset federal taxable income and state net operating loss carryforwards in amounts which vary by state. The federal net operating losses will expire beginning in 2030 and ending in 2036 and the state net operating losses will expire beginning in 2023 and ending in 2034. The use of these carryforwards is subject to annual limitations.