Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2014

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

	December 31,
	2014		2013
Coal & other plant and equipment	3,726,514		3,681,051
Intangible drilling cost	2,798,394		1,937,336
Proven properties	1,768,007		1,670,404
Unproven properties	1,540,835		1,463,406
Coal properties and surface lands	1,358,306		1,404,056
Gathering equipment	1,088,238		1,058,008
Wells and related equipment	716,748		688,548
Airshafts	468,924		397,466
Leased coal lands	263,946		393,372
Coal advance mining royalties	386,245		381,348
Mine development	414,501		354,607
Other gas assets	123,539		126,239
Gas advance royalties	20,580		22,668
Total Property, Plant and Equipment	14,674,777		13,578,509
Less Accumulated Depreciation, Depletion and Amortization	4,512,305		4,136,247
Total Net Property, Plant and Equipment	$	10,162,472	$	9,442,262

Schedule of Amortization Expense Per Unit of Production [Table Text Block]

	December 31,
	2014		2013
Unproven gas properties	$	1,540,835	$	1,463,406
Coal properties	477,444		273,242
Mine development	11,984		238,356
Leased coal lands	50,044		99,506
Coal advance mining royalties	52,009		48,043
Airshafts	52,194		38,794
Gas advance royalties	20,580		22,668
Total	$	2,205,090	$	2,184,015