Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock shares authorized (in shares)	15,000,000	15,000,000
Preferred stock shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock shares authorized (in shares)	100,000,000	100,000,000
Common stock shares issued (in shares)	35,699,819	34,781,201
Common stock shares outstanding (in shares)	33,628,109	33,091,223
Less shares held in treasury at cost (in shares)	2,071,710	1,689,978