Other Expense (Tables)

6 Months Ended

Jun. 30, 2012

Other Expense [Abstract]

Schedule of components of other expense

The following table provides the components of the Company's other expense:

	Three Months Ended June 30,						Six Months Ended June 30,
	2012			2011			2012		2011
	(in thousands)
Transportation commitment charges (a)	$	9,227		$	5,688		$	17,680	$	10,960
Above market drilling rig rates (b)	5,760			5,410			10,746		10,569
Terminated drilling rig contract charges (c)	8,960			—			8,960		—
Inventory valuation charges (d)	1,262			302			7,454		587
Other	4,578			(934		)	6,346		2,549
Premier Silica acquisition costs	1,190			—			2,173		—
Contingency and environmental accrual adjustments	(326		)	1,587			702		2,882
Loss on extinguishment of debt	—			—			197		2,367
Total other expense	$	30,651		$	12,053		$	54,258	$	29,914