Annual report pursuant to Section 13 and 15(d)

CONSOLIDATED BALANCE SHEETS (Parenthetical)

v3.8.0.1
CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares
Dec. 31, 2017
Dec. 31, 2016
Stock Transactions, Parenthetical Disclosures [Abstract]    
Preferred stock par value (in usd per share) $ 0.001 $ 0.001
Preferred stock shares authorized (in shares) 10,000,000 10,000,000
Preferred stock shares issued (in shares) 0 0
Preferred stock shares outstanding (in shares) 0 0
Common stock par value (in usd per share) $ 0.001 $ 0.001
Common stock shares authorized (in shares) 100,000,000 100,000,000
Common stock shares issued (in shares) 53,931,167 53,582,250
Common stock shares outstanding (in shares) 48,606,425 50,705,933