CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Disclosures of Cash Flow Information Cash payments for:
Interest, net of capitalized interest	$ 396	$ 486	$ 215
Other cash flow information:
Exchange of equipment for new equipment purchase	14,533	20,307	2,923
Increase (Decrease) in accounts payable	$ 7,635	$ 24,675