CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
CONDENSED CONSOLIDATED BALANCE SHEETS
Convertible senior notes, interest rate (as a percent)	2.50%
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	58,750,000	58,750,000
Common stock, shares issued	21,877,192	21,772,571
Common stock, shares outstanding	21,877,192	21,772,571