Consolidated Statements of Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Total Revenue	$ 164,562		$ 204,525		$ 324,195		$ 376,322
COSTS AND EXPENSES
Costs applicable to sales	118,687	[1]	142,386	[1]	225,583	[1]	230,444	[1]
Amortization	41,422		56,894		81,849		106,589
General and administrative	9,398		15,026		23,294		25,253
Exploration	5,153		6,774		9,370		13,615
Loss Related to Litigation Settlement	0		32,046		0		32,046
Pre-development, reclamation, and other	8,760		1,817		15,775		7,163
Total cost and expenses	183,420		254,943		355,871		415,110
OTHER INCOME (EXPENSE), NET
Fair value adjustments, net	(8,282)		66,754		(19,717)		84,550
Impairment of marketable securities	(934)		(17,192)		(3,522)		(17,227)
Interest and other income	(116)		419		(2,100)		4,275
Interest expense, net of capitalized interest	(12,310)		(10,930)		(25,365)		(20,662)
Total other income and expense	(21,642)		39,051		(50,704)		50,936
Income before income taxes	(40,500)		(11,367)		(82,380)		12,148
Income tax benefit (expense)	(2,621)		(23,673)		2,068		(34,918)
NET INCOME (LOSS)	(43,121)		(35,040)		(80,312)		(22,770)
Other Comprehensive Income (Loss), Net of Tax:
Unrealized loss on marketable securities, net of tax of $487 and $253 for the three and six months ended June 30, 2014, respectively	(773)		(7,491)		(401)		(11,057)
Reclassification adjustments for impairment of marketable securities, net of tax of $(362) and $(1,363) for the three and six months ended June 30, 2014, respectively	572		17,192		2,159		17,227
Reclassification adjustments for realized loss on sale of marketable securities, net of tax of $(10) for the three and six months ended June 30, 2014, respectively	17		0		17		0
Other comprehensive income (loss)	(184)		9,701		1,775		6,170
COMPREHENSIVE INCOME	$ (43,305)		$ (25,339)		$ (78,537)		$ (16,600)
BASIC AND DILUTED INCOME PER SHARE
Basic (in dollars per share)	$ (0.42)		$ (0.35)		$ (0.78)		$ (0.24)
Diluted (in dollars per share)	$ (0.42)		$ (0.35)		$ (0.78)		$ (0.24)

[1] Excludes amortization.