Other Long-Term Obligations (Tables)

12 Months Ended

Dec. 31, 2011

Dec. 31, 2010

Other Long-Term Obligations

Schedule of federal coal lease obligations

	2011		2010
Federal coal lease obligations, current	$	102,198	$	54,630
Federal coal lease obligations, noncurrent		186,119		63,659
Total federal coal lease obligations	$	288,317	$	118,289

Schedule of payments for federal coal lease obligations

						2011				2010
Payment Dates	Annual Payment		Imputed Interest Rate			Carrying Value		Fair Value(1)		Carrying Value		Fair Value
December 1, 2007 - 2011	$	3,980		6.80	%	$	—	$	—	$	3,728	$	3,868
August 1, 2008 - 2012	$	50,160		7.50	%		46,661		48,867		90,068		96,447
May 1, 2009 - 2013	$	9,620		8.70	%		16,998		18,517		24,493		27,298
July 1, 2011 - 2015	$	59,545		8.50	%		192,892		215,796		—		—
September 1, 2011 - 2015	$	9,862		8.50	%		31,766		35,293		—		—
						$	288,317	$	318,473	$	118,289	$	127,613

(1)

The fair value of estimates for federal coal lease obligations were determined by discounting the remaining lease payments using a current estimate of the credit-adjusted, risk-free rate based on our current credit rating.

Schedule of future payments on federal coal leases

Year Ended December 31,
2012	$	129.2
2013		79.0
2014		69.4
2015		69.4
Total		347.0
Less: imputed interest		58.7
Total principal payments		288.3
Less: current portion		102.2
Long-term federal coal leases payable	$	186.1

Schedule of imputed interest

	2011		2010		2009
Imputed interest	$	19,619	$	11,672	$	14,183

Schedule of purchase obligations in connection with the acquisitions of land and mineral rights

	2011	2010
Purchase obligations, total	$6,567	$8,071
Interest rate	6% - 8%	6% - 8%