CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Discount of notes	$ 66,338	$ 70,468
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	4,000,000	4,000,000
Preferred stock, shares issued
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	73,871,000	73,083,000
Common stock, shares outstanding	73,871,000	73,083,000
Senior Convertible Notes Due 2018
Discount of notes	24,383	25,354
Senior Notes Due 2019
Discount of notes	$ 41,955	$ 45,114