Condensed Consolidated Statements Of Income (USD $) In Thousands, except Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
SALES AND OPERATING REVENUES:
Coal sales	$ 442,483	$ 385,905	$ 850,168	$ 750,064
Transportation revenues	8,706	8,821	18,006	18,526
Other sales and operating revenues	6,757	5,617	13,030	12,414
Total revenues	457,946	400,343	881,204	781,004
EXPENSES:
Operating expenses (excluding depreciation, depletion and amortization)	284,117	246,702	540,235	485,969
Transportation expenses	8,706	8,821	18,006	18,526
Outside coal purchases	5,842	4,544	9,631	6,386
General and administrative	13,002	11,628	25,422	22,329
Depreciation, depletion and amortization	39,100	35,677	76,962	71,973
Total operating expenses	350,767	307,372	670,256	605,183
INCOME FROM OPERATIONS	107,179	92,971	210,948	175,821
Interest expense (net of interest capitalized for the three and six months ended June 30, 2011 and 2010 of $167, $423, $312 and $691, respectively)	(9,156)	(7,439)	(18,466)	(15,034)
Interest income	87	48	192	99
Other income	393	304	980	154
INCOME BEFORE INCOME TAXES	98,503	85,884	193,654	161,040
INCOME TAX EXPENSE	325	423	96	591
NET INCOME	98,178	85,461	193,558	160,449
GENERAL PARTNERS' INTEREST IN NET INCOME	22,209	17,957	43,214	34,999
LIMITED PARTNERS' INTEREST IN NET INCOME	$ 75,969	$ 67,504	$ 150,344	$ 125,450
BASIC NET INCOME PER LIMITED PARTNER UNIT (Note 7)	$ 2.04	$ 1.82	$ 4.03	$ 3.38
DILUTED NET INCOME PER LIMITED PARTNER UNIT (Note 7)	$ 2.04	$ 1.82	$ 4.03	$ 3.38
DISTRIBUTIONS PAID PER LIMITED PARTNER UNIT	$ 0.89	$ 0.79	$ 1.75	$ 1.565
WEIGHTED AVERAGE NUMBER OF UNITS OUTSTANDING - BASIC	36,775,741	36,716,855	36,762,402	36,703,901
WEIGHTED AVERAGE NUMBER OF UNITS OUTSTANDING - DILUTED	36,775,741	36,716,855	36,762,402	36,703,901