CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Valuation allowance	$ 43,718	$ 43,610
Common stock, shares authorized (in shares)	90,000,000	90,000,000
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares issued (in shares)	25,096,087	24,962,477
Common stock, shares outstanding (in shares)	24,937,865	24,819,066
Treasury stock, at cost	158,222	143,411