Comprehensive Income (Tables)

9 Months Ended

Sep. 30, 2011

Comprehensive Income [Abstract]

Components Of Comprehensive Income

		Three Months Ended September 30					Nine Months Ended September 30
	2011			2010		2011			2010
	(In thousands)					(In thousands)
Net income attributable to Arch Coal, Inc.	$	19,056		$	46,678	$	82,128		$	111,038
Other comprehensive income, net of income taxes:
Pension, postretirement and other post-employment benefits,
reclassifications into net income		388			28		1,254			84
Unrealized gains (losses) on available-for-sale securities		(569	)		738		(1,256	)		(178	)
Unrealized gains and losses on derivatives, net of
reclassifications into net income:
Unrealized gains (losses) on derivatives		(3,671	)		1,200		2,703			(3,889	)
Reclassifications of (gains) losses into net income		(3,575	)		639		(10,059	)		1,856
Total comprehensive income	$	11,629		$	49,283	$	74,770		$	108,911