Condensed Consolidated Statements Of Financial Position (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
CURRENT ASSETS:
Cash and cash equivalents	$ 702	$ 461
Accounts receivable, net of allowance for doubtful accounts ($0 as of March 31, 2013 and December 31, 2012)	34,221	33,560
Inventories	15,037	18,743
Advance royalties, current portion	28	187
Prepaid expenses and other	3,363	4,323
Total current assets	53,351	57,274
PROPERTY, PLANT AND EQUIPMENT:
At cost, including coal properties, mine development and construction costs	682,949	683,669
Less accumulated depreciation, depletion and amortization	(225,484)	(219,709)
Net property, plant and equipment	457,465	463,960
Advance royalties, net of current portion	5,023	4,506
Investment in unconsolidated affiliates	22,964	23,659
Intangible assets, net	1,207	1,228
Other non-current assets	9,176	8,831
TOTAL	549,186	559,458
CURRENT LIABILITIES:
Accounts payable	16,139	18,030
Accrued expenses and other	17,689	22,178
Current portion of long-term debt	1,376	2,350
Current portion of asset retirement obligations	2,438	2,255
Current portion of postretirement benefits	227	227
Total current liabilities	37,869	45,040
NON-CURRENT LIABILITIES:
Long-term debt, net of current portion	165,231	161,199
Asset retirement obligations, net of current portion	30,813	30,748
Other non-current liabilities	10,224	10,309
Postretirement benefits, net of current portion	6,619	6,520
Total non-current liabilities	212,887	208,776
Total liabilities	250,756	253,816
COMMITMENTS AND CONTINGENCIES (NOTE 13)
PARTNERS' CAPITAL:
Limited partners	285,869	292,791
General partner	11,167	11,420
Accumulated other comprehensive income	1,394	1,431
Total partners' capital	298,430	305,642
TOTAL	$ 549,186	$ 559,458