Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2016	Dec. 31, 2015
Condensed Consolidated Balance Sheets
Convertible senior notes interest rate	2.00%	2.00%
Preferred stock, par value	$ 0.001	$ 0.001
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	$ 0.001	$ 0.001
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	30,755,000	30,715,000
Common stock, shares outstanding	29,504,000	29,464,000
Treasury stock, shares	1,251,297	1,251,297