CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplemental Disclosures of Cash Flow Information Cash payments for:
Interest, net of capitalized interest	$ 486	$ 215	$ 488
Other cash flow information:
Exchange of equipment for new equipment purchase	20,307	2,923
Increase (Decrease) in accounts payable	$ 24,675