Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

The components of income tax expense (benefit) were as follows:

	For The Years Ended December 31,
	2017			2016			2015
Current:
U.S. Federal	$	65,856		$	(76,447	)	$	49,435
U.S. State	2,732			(1,924		)	2,591
Non-U.S.	2,030			1,411			963
	70,618			(76,960		)	52,989
Deferred:
U.S. Federal	17,397			89,268			66,187
U.S. State	(787		)	2,257			6,429
	16,610			91,525			72,616
Total Income Tax Expense	$	87,228		$	14,565		$	125,605

Schedule of Reconciliation of Income Tax Expense (Benefit)

A reconciliation of income tax expense (benefit) and the amount computed by applying the statutory federal income tax rate of 35% to income from operations before income tax is:

	For the Years Ended December 31,
	2017					2016					2015
	Amount			Percent		Amount			Percent		Amount			Percent
Statutory U.S. federal income tax rate	$	59,429		35.0	%	$	22,755		35.0	%	$	155,059		35.0	%
State income taxes, net of federal tax benefit	1,264			0.7		997			1.5		6,767			1.5
Excess tax depletion	(24,216		)	(14.3	)	(21,856		)	(33.6	)	(27,720		)	(6.3	)
Effect of domestic production activities	(6,493		)	(3.8	)	1,621			2.5		(4,933		)	(1.1	)
Effect of change in U.S. tax law	58,558			34.5		—			—		—			—
IRS and state tax examination settlements	—			—		13,958			21.5		—			—
Effect of valuation allowance	1,379			0.8		—			—		—			—
Other	(2,693		)	(1.6	)	(2,910		)	(4.5	)	(3,568		)	(0.8	)
Income Tax Expense / Effective Rate	$	87,228		51.3	%	$	14,565		22.4	%	$	125,605		28.3	%

Schedule of Significant Components of Deferred Tax Assets and Liabilities

Significant components of deferred tax assets and liabilities were as follows:

	December 31,
	2017			2016
Deferred Tax Asset:
Postretirement benefits other than pensions	$	131,354		$	255,507
Asset retirement obligations	51,415			99,467
Pneumoconiosis benefits	36,160			43,371
Workers' compensation	16,778			28,530
Mine subsidence	15,322			39,251
Salary retirement	12,465			37,498
State bonus, net of Federal	4,473			3,175
Long-term disability	3,375			6,358
Other	7,924			8,042
Total Deferred Tax Asset	279,266			521,199
Valuation Allowance	(1,379		)	—
Net Deferred Tax Asset	277,887			521,199
Deferred Tax Liability:
Property, plant and equipment	(174,806		)	(256,947		)
Equity Partnerships	(17,991		)	(67,498		)
Advance mining royalties	(10,025		)	(12,175		)
Total Deferred Tax Liability	(202,822		)	(336,620		)
Net Deferred Tax Asset	$	75,065		$	184,579