7 .	Income Taxes

Income tax expense attributable to earnings before income taxes consists of (in thousands):

	Years ended December 31,
	201 7			201 6		201 5
Current:
Federal	$	134,284		$	191,422	$	160,235
State and local		23,456			21,871		22,306
		157,740			213,293		182,541
Deferred:
Federal		(261,592	)		45,846		71,292
State and local		12,828			4,568		9,135
		(248,764	)		50,414		80,427
Tot al tax expense/(benefit)	$	(91,024	)	$	263,707	$	262,968

Income tax expense attributable to earnings before income taxes differed from the amounts computed using the statutory federal income tax rate of

35%

as follows (in thousands):

	Years ended December 31,
	201 7			201 6			201 5
Income tax at federal statutory rate	$	208,334		$	243,529		$	241,571
State tax, net of federal effect		18,334			19,165			18,671
Federal tax reform		(309,223	)		-			-
Benefit of stock compensation		(4,907	)		-			-
199/R&D credit		(7,056	)		-			-
Nondeductible meals and entertainment		1,374			1,419			1,420
Change in effective state tax rate, net of federal benefit		3,403			(1,055	)		1,761
Other, net		(1,283	)		649			(455	)
Total tax expense	$	(91,024	)	$	263,707		$	262,968

The Tax Cuts and Jobs Act (the Act) was enacted

December 2017.

Beginning in

2018,

the Act reduces the U.S. federal corporate tax rate from

35%

21%.

December 31, 2017,

we had

not

completed our accounting for the tax effects of enactment of the Act. However, we have made a reasonable estimate of the effects on our existing deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally

21%.

The provisional amount recorded resulting from the remeasurement of our deferred tax balance was

$309.2

million, which is included as a component of income tax from continuing operations. We are still refining our calculations for our

2017

federal income tax return, which will be filed based on the law prior to the Act, and could potentially affect the measurement of these balances. Remaining aspects of the Act are

not

relevant to our operations.

Income taxes receivable

was

$61.3

million and

$15.7

million at

December 31, 2017

and

2016,

respectively. These amounts have been included in other receivables in our Consolidated Balance Sheets. The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities at

December 31, 2017

and

2016,

are presented below (in thousands):

	December 31,
	201 7			201 6
Deferred tax assets:
Insurance accruals	$	27,700		$	34,788
Allowance for doubtful accounts		6,605			2,347
Compensation accrual		3,661			10,443
Deferred compensation accrual		17,620			26,062
Federal benefit of state uncertain tax positions		8,681			14,085
State NOL carry-forward		4,944			3,444
Other		3,134			3,853
Total gross deferred tax assets		72,345			95,022
Valuation allowance		(4,944	)		(3,444	)
Total deferred tax assets, net of valuation allowance		67,401			91,578
Deferred tax liabilities:
Plant and equipment, principally due to differences in depreciation		566,396			831,555
Prepaid permits and insurance, principally due to expensing for income tax purposes		28,089			37,119
Other		14,786			13,538
Total gross deferred tax liabilities		609,271			882,212
Net deferred tax liability	$	541,870		$	790,634

Guidance on accounting for uncertainty in income taxes prescribes recognition and measurement criteria and requires that we assess whether the benefits of our tax positions taken are more likely than

not

of being sustained under tax audits.

We have made adjustments to the balance of unrecognized tax benefits, a component of other long-term liabilities on our Consolidated Balance Sheets, as follows (in millions):

	December 31,
	201 7			201 6			201 5
Beginning balance	$	35.4		$	32.0		$	31.6
Additions based on tax positions related to the current year		11.6			10.3			9.4
Additions/(reductions) based on tax positions taken in prior years		5.4			(3.2	)		(2.5	)
Reductions due to settlements		(2.4	)		(0.4	)		(3.0	)
Reductions due to lapse of applicable statute of limitations		(4.7	)		(3.3	)		(3.5	)
Ending balance	$	45.3		$	35.4		$	32.0

December 31,

201

and

2016,

we had a total of

$45.3

million and

$35.4

million, respectively, in gross unrecognized tax benefits. Of these amounts,

$37.5

million and

$23.0

million represent the amount of unrecognized tax benefits that, if recognized, would impact our effective tax rate in

2017

and

2016,

respectively. Interest and penalties related to income taxes are classified as interest expense in our Consolidated Statements of Earnings. The amount of accrued interest and penalties recognized during the years ended

December 31, 2017,

2016,

and

2015,

was

$2.1

million,

$1.9

million, and

$1.9

million, respectively. Future changes to unrecognized tax benefits will be recognized as income tax expense and interest expense, as appropriate. The total amount of accrued interest and penalties for such unrecognized tax benefits at

December 31, 2017

and

2016,

was

$3.6

million and

$4.4

million, respectively.

Tax years

201

and forward remain subject to examination by federal tax jurisdictions, while tax years

2007

and forward remain open for state jurisdictions.