SHAREHOLDERS' EQUITY (Common Stock,Preferred Stock and Rights Agreement) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	Feb. 29, 2012	Dec. 31, 2012 series class	Dec. 31, 2011	Dec. 31, 2010
Class of Stock
Common stock, authorized (in shares)		200,000,000
Common stock, par value per share (in dollars per share)		$ 0.1
Common stock, issued (in shares)		118,245,320	114,525,673
Common stock, outstanding (in shares)		118,245,320	114,525,673
Stock issued as partial consideration of acquisition of unproved oil and gas properties (in shares)	2,657,000
Value of stock issued as partial consideration of acquisition of unproved oil and gas properties	$ 36,431	$ 36,431	$ 0	$ 0
Preferred stock, authorized (in shares)		10,000,000
Preferred stock, par value per share (in dollars per share)		$ 0.01
Preferred stock, number of classes of preferred stock		2
Preferred stock, minimum number of series that preferred stock is issuable		1
Rights agreement, number of preferred shares purchased for each preferred share purchase right redeemed (in shares)		0.01
Rights agreement, preferred share initial purchase price (in dollars per share)		$ 120
Rights agreement, minimum percentage of common stock acquired to exercise Preferred Share Purchase Right (as a percent)		20.00%
Rights agreement, minimum percentage of common stock that must be acquired through tender offer to exercise Preferred Share Purchase Right (as a percent)		20.00%
Senior Preferred Stock
Class of Stock
Preferred stock, authorized (in shares)		7,400,000
Junior Preferred Stock
Class of Stock
Preferred stock, authorized (in shares)		2,700,000