Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Summary of Income Tax Expense Allocated Based on Separate Tax Return Basis

Income tax expense, allocated based on a separate tax return basis, consists of the following:

Year Ended December 31	2014		2013			2012
Current income taxes:
Federal taxes	$	18,111	$	33,614		$	22,182
State taxes		396		(116	)		416
		18,507		33,498			22,598
Deferred income taxes:
Federal taxes		44,113		11,258			21,175
State taxes		—		—			—
		44,113		11,258			21,175
	$	62,620	$	44,756		$	43,773

Summary of Reconciliation Between the Statutory Tax Rate and Actual Effective Tax Rate

The following table provides a reconciliation between the statutory tax rate and the actual effective tax rate:

Year Ended December 31	2014			2013			2012
Statutory tax rate		35.0	%		35.0	%		35.0	%
Effect of tax-free interest and dividend income		(3.1	)		(4.3	)		(4.7	)
Tax credits and settlements		(1.4	)		(2.4	)		(1.8	)
Life insurance		—			(0.4	)		—
Other items		(0.2	)		(0.4	)		(0.1	)
Actual effective tax rate		30.3	%		27.5	%		28.4	%

Summary of Deferred Tax Assets and Liabilities from Tax Effects of Temporary Differences

The following table presents the tax effects of temporary differences that give rise to deferred tax assets and liabilities:

December 31	2014			2013
Deferred tax assets:
Allowance for loan losses	$	44,613		$	39,292
Discount on purchased loans		31,787			41,012
Net operating loss/tax credit carryforwards		15,367			17,052
Deferred compensation		7,785			8,208
Securities impairments		412			20,371
Pension and other defined benefit plans		6,871			2,190
Net unrealized securities losses		—			13,295
Other		9,503			3,567
Total		116,338			144,987
Valuation allowance		(15,505	)		(15,611	)
Total deferred tax assets		100,833			129,376
Deferred tax liabilities:
Loan costs		(1,497	)		(931	)
Depreciation		(11,533	)		(9,819	)
Prepaid expenses		(705	)		(1,261	)
Amortizable intangibles		(13,842	)		(11,346	)
Lease financing		(7,302	)		(6,290	)
Debt discharge income deferral		(2,829	)		(3,402	)
Originated mortgage servicing rights		(2,721	)		(2,721	)
Other		—			(1,214	)
Total deferred tax liabilities		(40,429	)		(36,984	)
Net deferred tax assets	$	60,404		$	92,392

Summary of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits (excluding interest and the federal income tax benefit of unrecognized state tax benefits) is as follows:

Year Ended December 31	2014			2013
Balance at beginning of year	$	660		$	1,088
Additions based on tax positions related to current year		60			74
Additions based on tax positions of prior year		—			—
Reductions for tax positions of prior years		—			—
Reductions due to expiration of statute of limitations		(319	)		(502	)
Balance at end of year	$	401		$	660