CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2012	Dec. 31, 2011
CONSOLIDATED BALANCE SHEETS
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	260,000,000	260,000,000
Common stock, shares issued	166,625,976	165,892,170
Common stock, shares outstanding	166,604,427	165,871,905
Treasury stock, shares	21,549	20,265