Income Taxes (Details 2) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Income Tax Disclosure [Abstract]
Amount computed using the statutory rate	$ (45,655)		$ 3,058		$ 17,065
State & local taxes	(2,870)		192		1,073
Percentage depletion carryforward	(1,309)		(2,507)		(252)
Allowance for alternative minimum tax	0		8		575
Share-based compensation	292	[1]	183	[1]	295	[1]
Effective Income Tax Reconciliation, Write-off of Deferred Tax Assets	9	[2]	346	[2]	3,041	[2]
Other	303		(300)		321
Change in valuation allowance	50,866		(2,790)		(20,488)
Income tax expense (benefit)	$ 1,636		$ (1,810)		$ 1,630

[1] Relates to compensation expense recognized on the vesting of Incentive Stock Options.

[2] Relates to the write-off of deferred tax assets associated with share based compensation that will not be recognized for tax purposes.