Income Taxes

Income tax expense was as follows:



	2016			2015			2014
Current income tax expense	$	48,748		$	59,530		$	62,177
Deferred income tax expense (benefit)	(11,598		)	(19,059		)	(4,130		)
Income tax expense, as reported	$	37,150		$	40,471		$	58,047

A reconciliation between reported income tax expense and the amounts computed by applying the U.S. federal statutory income tax rate of 35% to income before income taxes is presented in the following table. During 2016, we adopted a new accounting standard that impacted how the income tax effects associated with stock-based compensation are recognized. See Note 1 - Significant Accounting Policies for additional information.



	2016			2015			2014
Income tax expense computed at the statutory rate	$	119,494		$	111,930		$	117,608
Effect of tax-exempt interest	(75,696		)	(70,889		)	(58,761		)
Bank owned life insurance income	(1,260		)	(1,255		)	(1,116		)
Net tax benefit from stock-based compensation	(5,063		)	—			—
Other	(325		)	685			316
Income tax expense, as reported	$	37,150		$	40,471		$	58,047

Year-end deferred taxes were as follows:



	2016			2015
Deferred tax assets:
Allowance for loan losses	$	53,566		$	47,551
Alternative minimum tax carryforward, no expiration date	30,384			10,934
Net actuarial loss on defined benefit post-retirement benefit plans	21,956			25,172
Stock-based compensation	18,140			21,246
Bonus accrual	7,035			5,832
Gain on sale of assets	2,485			2,044
Transaction costs	1,587			1,716
Other	4,449			5,718
Total gross deferred tax assets	139,602			120,213
Deferred tax liabilities:
Premises and equipment	(33,777		)	(23,038		)
Defined benefit post-retirement benefit plans	(14,828		)	(14,089		)
Intangible assets	(11,697		)	(8,940		)
Net unrealized gain on securities available for sale and transferred securities	(8,699		)	(86,484		)
Leases	(3,042		)	(4,491		)
Section 481(a) change in accounting method (tangible property)	(1,694		)	(3,387		)
Prepaid expenses	(1,743		)	(1,702		)
Other	(436		)	(563		)
Total gross deferred tax liabilities	(75,916		)	(142,694		)
Net deferred tax asset (liability)	$	63,686		$	(22,481	)

No valuation allowance for deferred tax assets was recorded at December 31, 2016 and 2015 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 2013.