Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowances for contract receivables	$ 1,499	$ 799
Allowances for employee advances and miscellaneous receivables	292	500
Accumulated amortization on intangible assets	$ 40,461	$ 36,128
Common stock, par value (usd per share)	$ 0	$ 0
Common stock, stated value per share (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	50,000,000	50,000,000
Common stock, shares issued (shares)	22,419,417	21,845,920
Common stock, shares outstanding (shares)	22,419,417	21,845,920