Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Current and Deferred Income Tax Expense (Benefit)

The current and deferred amounts of income tax expense (benefit) were as follows.



	Years Ended December 31,
	2016		2015			2014
	($ in Thousands)
Current:
Federal	$	73,781	$	82,449		$	74,646
State	2,885		2,560			1,000
Total current	76,666		85,009			75,646
Deferred:
Federal	3,338		(10,606		)	(805		)
State	7,318		7,084			10,695
Total deferred	10,656		(3,522		)	9,890
Total income tax expense	$	87,322	$	81,487		$	85,536

Schedule of Deferred Tax Assets and Liabilities

Temporary differences between the amounts reported in the financial statements and the tax bases of assets and liabilities resulted in deferred taxes. Deferred tax assets and liabilities at December 31 were as follows.



	2016		2015
	($ in Thousands)
Deferred tax assets:
Allowance for loan losses	$	100,891	$	106,258
Allowance for other losses	11,080		10,906
Accrued liabilities	5,969		6,802
Deferred compensation	33,169		31,677
State net operating losses	7,882		14,154
Nonaccrual interest	1,085		1,901
Net unrealized losses on available-for-sale securities	16,980		219
Net unrealized losses on pension and postretirement benefits	21,218		20,404
Other	8,128		5,811
Total deferred tax assets	206,402		198,132
Deferred tax liabilities:
FHLB stock dividends	—		2,165
Prepaid expenses	70,943		69,396
Goodwill	27,365		25,770
Mortgage banking activities	17,569		15,704
Deferred loan fee income	16,474		17,770
State deferred taxes	3,800		6,366
Lease financing	1,975		3,042
Bank premises and equipment	7,698		7,491
Other	8,594		9,062
Total deferred tax liabilities	154,418		156,766
Net deferred tax assets	$	51,984	$	41,366

Schedule of Effective Income Tax Rate Reconciliation

The effective income tax rate differs from the statutory federal tax rate. The major reasons for this difference were as follows.



	2016		2015		2014
Federal income tax rate at statutory rate	35.0	%	35.0	%	35.0	%
Increases (decreases) resulting from:
Tax-exempt interest and dividends	(4.8	)%	(5.0	)%	(4.6	)%
State income taxes (net of federal benefit)	2.3	%	2.3	%	2.8	%
Bank owned life insurance	(1.7	)%	(1.2	)%	(1.7	)%
Tax effect of tax credits and benefits, net of related expenses	(0.8	)%	(0.5	)%	(1.4	)%
Tax reserve adjustments	0.3	%	(0.6	)%	0.7	%
Other	0.1	%	0.2	%	0.2	%
Effective income tax rate	30.4	%	30.2	%	31.0	%

Summary Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits was as follows.



	2016		2015
	($ in Millions)
Balance at beginning of year	$	9	$	9
Subtractions for tax positions related to prior years	—		(2		)
Additions for tax positions related to current year	1		2
Balance at end of year	$	10	$	9