Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
Condensed Consolidated Balance Sheets
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	44,402,827	43,174,676
Common stock, shares outstanding (in shares)	33,766,673	32,854,802
Treasury stock, shares (in shares)	10,636,154	10,319,874