UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Other cash flow information:
Exchange of equipment for new equipment purchase	$ 10,778,000
Capital expenditures	$ 25,000,000	$ 25,000,000