Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of components of income tax expenses

The following table presents the components of income tax expense for the years ended December 31, 2019, 2018 and 2017:

($ in thousands)	Year Ended December 31,
	2019			2018			2017
Current income tax expense (benefit):
Federal	$	107,393		$	63,035		$	120,968
State	86,578			64,917			72,837
Foreign	(2,485		)	3,513			1,815
Total current income tax expense	191,486			131,465			195,620
Deferred income tax (benefit) expense:
Federal	(8,801		)	(11,870		)	40,057
State	(16,390		)	(4,600		)	(6,201		)
Foreign	3,587			—			—
Total deferred income tax (benefit) expense	(21,604		)	(16,470		)	33,856
Income tax expense	$	169,882		$	114,995		$	229,476

Schedule of reconciliation of the federal statutory rate to the effective income tax rate

The following table presents the reconciliation of the federal statutory rate to the Company’s effective tax rate for the years ended December 31, 2019, 2018 and 2017:

	Year Ended December 31,
	2019		2018		2017
Statutory U.S. federal tax rate	21.0	%	21.0	%	35.0	%
U.S. state income taxes, net of U.S. federal income tax effect	7.1		5.8		5.9
The Tax Act	—		0.1		4.5
Tax credits and affordable housing, net of amortization	(10.4	)	(13.3	)	(15.1	)
Other, net	2.4		0.4		0.9
Effective tax rate	20.1	%	14.0	%	31.2	%

Schedule of tax effects of temporary differences that give rise to a significant portion of the deferred tax assets and liabilities

The tax effects of temporary differences that give rise to a significant portion of deferred tax assets and liabilities as of December 31, 2019 and 2018 are presented below:

($ in thousands)	December 31,
	2019			2018
Deferred tax assets:
Allowance for loan losses	$	109,903		$	96,876
Investments in qualified affordable housing partnerships, tax credit and other investments, net	11,190			3,691
Deferred compensation	23,816			18,724
Interest income on nonaccrual loans	9,527			8,602
State taxes	5,848			4,506
Unrealized gains/losses on securities	324			20,233
Tax credit carryforwards	—			26,831
Premises and equipment	1,578			1,887
Deferred gain	—			4,476
Lease liability	35,948			2,604
Other	641			6,178
Total gross deferred tax assets	198,775			194,608
Valuation allowance	(21		)	(128		)
Total deferred tax assets, net of valuation allowance	$	198,754		$	194,480
Deferred tax liabilities:
Equipment lease financing	$	30,669		$	30,523
Investments in qualified affordable housing partnerships, tax credit and other investments, net	12,301			30,706
Core deposit intangibles	3,032			4,427
FHLB stock dividends	1,854			1,866
Mortgage servicing assets	1,839			2,390
Acquired debt	1,679			1,771
Prepaid expenses	1,100			1,207
Premises and equipment	1,890			1,078
Operating lease right-of-use assets	34,313			—
Other	3,590			2,872
Total gross deferred tax liabilities	$	92,267		$	76,840
Net deferred tax assets	$	106,487		$	117,640

Summary of reconciliation of the beginning and ending amount of unrecognized tax benefits

The following table presents a reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended December 31, 2019, 2018 and 2017:

($ in thousands)	Year Ended December 31,
	2019			2018			2017
Beginning balance	$	4,378		$	10,419		$	10,419
Additions for tax positions related to prior years	30,103			—			—
Deductions for tax positions related to prior years	(34,481		)	(3,969		)	—
Settlements with taxing authorities	—			(2,072		)	—
Ending balance	$	—		$	4,378		$	10,419