CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Other property and equipment, accumulated depreciation (in dollars)	$ 20,821,000	$ 10,714,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares	200,000,000	200,000,000
Common stock, issued shares	66,121,809	64,145,482
Common stock, outstanding, net of treasury shares	66,071,228	64,064,415
Treasury stock, shares	50,581	81,067
Convertible Debt [Member]
Debt Instrument, Unamortized Discount	$ 0	$ 2,431,000
Interest rate on notes (as a percent)	3.50%	3.50%
6.625% Senior Notes [Member]
Interest rate on notes (as a percent)	6.625%	6.625%
6.50% Senior Notes [Member]
Interest rate on notes (as a percent)	6.50%	6.50%
6.50% Senior Notes due 2023 [Member]
Interest rate on notes (as a percent)	6.50%