Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2011

Fair Value Measurements (Tables) [Abstract]

Assets and liabilities measured at fair value on a recurring basis

			Markets for		Observable		Unobservable
	June 30,		Identical Assets		Inputs		Inputs
	2011		(Level 1)		(Level 2)		(Level 3)
Deferred compensation plan investments	$	13,422	$	13,422	$	—	$	—
Total assets measured at fair value	$	13,422	$	13,422	$	—	$	—
Variable to fixed natural gas swaps, net	$	220	$	—	$	220	$	—
Variable to fixed interest rate swaps		1,529		—		1,529		—
Total liabilities measured at fair value	$	1,749	$	—	$	1,749	$	—