Condensed Consolidated Statements of Operations - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Costs, expenses and other operating
Asset impairment and mine closure costs		$ 43,700,000
Successor
Revenues	$ 549,866,000		$ 1,150,841,000
Costs, expenses and other operating
Cost of sales (exclusive of items shown separately below)	435,038,000		896,448,000
Depreciation, depletion and amortization	30,701,000		62,622,000
Accretion on asset retirement obligations	7,623,000		15,246,000
Amortization of sales contracts, net	14,352,000		29,042,000
Change in fair value of coal derivatives and coal trading activities, net	863,000		1,717,000
Asset impairment and mine closure costs	0		0
Selling, general and administrative expenses	22,146,000		42,669,000
Other operating income, net	(3,549,000)		(5,859,000)
Total operating expenses	507,174,000		1,041,885,000
Income (loss) from operations	42,692,000		108,956,000
Interest expense, net
Interest expense	(6,003,000)		(15,428,000)
Interest and investment income	842,000		1,369,000
Interest expense, net	(5,161,000)		(14,059,000)
Income (loss) before nonoperating expenses	37,531,000		94,897,000
Nonoperating expenses
Net loss resulting from early retirement of debt and debt restructuring	(31,000)		(2,061,000)
Reorganization items, net	(21,000)		(2,849,000)
Nonoperating income (expense)	(52,000)		(4,910,000)
Income (loss) before income taxes	37,479,000		89,987,000
Provision for (benefit from) income taxes	319,000		1,159,000
Net income (loss)	$ 37,160,000		$ 88,828,000
Net income (loss) per common share
Basic earnings (loss) per common share (in dollars per share)	$ 1.51		$ 3.58
Diluted earnings (loss) per common share (in dollars per share)	$ 1.48		$ 3.52
Weighted average shares outstanding
Basic weighted average shares outstanding (shares)	24,659		24,834
Diluted weighted average shares outstanding (shares)	25,082		25,245
Dividends declared per common share (in dollars per share)	$ 0.35		$ 0.35
Predecessor
Revenues		420,298,000		$ 848,404,000
Costs, expenses and other operating
Cost of sales (exclusive of items shown separately below)		410,992,000		822,002,000
Depreciation, depletion and amortization		58,459,000		122,158,000
Accretion on asset retirement obligations		8,050,000		16,356,000
Amortization of sales contracts, net		1,000		(832,000)
Change in fair value of coal derivatives and coal trading activities, net		1,158,000		2,368,000
Asset impairment and mine closure costs		43,701,000		129,221,000
Selling, general and administrative expenses		19,019,000		38,845,000
Other operating income, net		(10,561,000)		(12,781,000)
Total operating expenses		530,819,000		1,117,337,000
Income (loss) from operations		(110,521,000)		(268,933,000)
Interest expense, net
Interest expense		(45,273,000)		(89,724,000)
Interest and investment income		933,000		2,071,000
Interest expense, net		(44,340,000)		(87,653,000)
Income (loss) before nonoperating expenses		(154,861,000)		(356,586,000)
Nonoperating expenses
Net loss resulting from early retirement of debt and debt restructuring		0		(2,213,000)
Reorganization items, net		(21,271,000)		(25,146,000)
Nonoperating income (expense)		(21,271,000)		(27,359,000)
Income (loss) before income taxes		(176,132,000)		(383,945,000)
Provision for (benefit from) income taxes		(245,000)		(1,356,000)
Net income (loss)		$ (175,887,000)		$ (382,589,000)
Net income (loss) per common share
Basic earnings (loss) per common share (in dollars per share)		$ (8.26)		$ (17.97)
Diluted earnings (loss) per common share (in dollars per share)		$ (8.26)		$ (17.97)
Weighted average shares outstanding
Basic weighted average shares outstanding (shares)		21,293		21,293
Diluted weighted average shares outstanding (shares)		21,293		21,293
Dividends declared per common share (in dollars per share)		$ 0		$ 0