Income Taxes

Income tax expense was as follows:



	2015			2014			2013
Current income tax expense	$	59,530		$	62,177		$	49,736
Deferred income tax expense (benefit)	(19,059		)	(4,130		)	3,279
Income tax expense, as reported	$	40,471		$	58,047		$	53,015

Reported income tax expense differed from the amounts computed by applying the U.S. federal statutory income tax rate of 35% to income before income taxes as follows:



	2015			2014			2013
Income tax expense computed at the statutory rate	$	111,930		$	117,608		$	101,808
Effect of tax-exempt interest	(70,889		)	(58,761		)	(46,535		)
Bank owned life insurance income	(1,255		)	(1,116		)	(1,086		)
Other	685			316			(1,172		)
Income tax expense, as reported	$	40,471		$	58,047		$	53,015

Year-end deferred taxes were as follows:



	2015			2014
Deferred tax assets:
Allowance for loan losses	$	47,551		$	34,840
Net actuarial loss on defined benefit post-retirement benefit plans	25,172			26,263
Stock-based compensation	21,246			18,839
Alternative minimum tax carryforward	10,934			—
Bonus accrual	5,832			6,118
Gain on sale of assets	2,044			2,139
Transaction costs	1,716			1,794
Partnerships	1,271			1,911
Other	4,447			5,272
Total gross deferred tax assets	120,213			97,176
Deferred tax liabilities:
Net unrealized gain on securities available for sale and effective cash flow hedging derivatives	(86,484		)	(102,626		)
Premises and equipment	(23,038		)	(20,039		)
Defined benefit post-retirement benefit plans	(14,089		)	(15,010		)
Intangible assets	(8,940		)	(6,143		)
Leases	(4,491		)	(4,952		)
Section 481(a) change in accounting method (tangible property)	(3,387		)	—
Prepaid expenses	(1,702		)	(1,639		)
Reserve for medical insurance	(211		)	(3,017		)
Other	(352		)	(341		)
Total gross deferred tax liabilities	(142,694		)	(153,767		)
Net deferred tax asset (liability)	$	(22,481	)	$	(56,591	)

No valuation allowance for deferred tax assets was recorded at December 31, 2015 and 2014 as management believes it is more likely than not that all of the deferred tax assets will be realized because they were supported by recoverable taxes paid in prior years. There were no unrecognized tax benefits during any of the reported periods.

We file income tax returns in the U.S. federal jurisdiction. We are no longer subject to U.S. federal income tax examinations by tax authorities for years before 2012.