Condensed Consolidated Statements Of Income (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
REVENUES
Coal sales	$ 985,087	$ 764,295	$ 1,858,025	$ 1,476,169
COSTS, EXPENSES AND OTHER
Cost of coal sales	709,953	570,861	1,363,637	1,121,611
Depreciation, depletion and amortization	95,183	87,759	178,720	176,278
Amortization of acquired sales contracts, net	1,489	5,214	7,433	15,967
Selling, general and administrative expenses	29,039	35,344	59,474	62,510
Change in fair value of coal derivatives and coal trading activities, net	2,672	4,587	888	10,464
Acquisition and transition costs related to ICG	48,666		48,666
Gain on Knight Hawk transaction		(41,577)		(41,577)
Other operating income, net	(4,732)	(4,392)	(5,848)	(7,783)
Total operating expenses	882,270	657,796	1,652,970	1,337,470
Income from operations	102,817	106,499	205,055	138,699
Interest expense, net:
Interest expense	(42,249)	(35,125)	(76,829)	(70,208)
Interest income	755	623	1,501	961
Interest expense, net	(41,494)	(34,502)	(75,328)	(69,247)
Other non-operating expense:
Bridge financing costs related to ICG	(49,490)		(49,490)
Net loss resulting from early retirement of ICG debt	(250)		(250)
Other non-operating expense, Total	(49,740)		(49,740)
Income before income taxes	11,583	71,997	79,987	69,452
Provision for income taxes	186	5,723	12,716	4,948
Net income	11,397	66,274	67,271	64,504
Less: Net income attributable to noncontrolling interest	(318)	(118)	(591)	(144)
Net income attributable to Arch Coal, Inc.	$ 11,079	$ 66,156	$ 66,680	$ 64,360
EARNINGS PER COMMON SHARE
Basic earnings per common share	$ 0.06	$ 0.41	$ 0.40	$ 0.40
Diluted earnings per common share	$ 0.06	$ 0.41	$ 0.39	$ 0.40
Basic weighted average shares outstanding	174,244	162,388	168,442	162,380
Diluted weighted average shares outstanding	175,272	163,130	169,554	163,105
Dividends declared per common share	$ 0.11	$ 0.1	$ 0.21	$ 0.19