Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowances for contract receivables	$ 1,016	$ 1,499
Allowances for employee advances and miscellaneous receivables	225	292
Accumulated amortization on intangible assets	$ 42,689	$ 40,461
Common stock, par value (usd per share)
Common stock, stated value per share (usd per share)	$ 0	$ 0
Common stock, shares authorized (shares)	50,000,000	50,000,000
Common stock, shares issued (shares)	23,611,680	22,419,417
Common stock, shares outstanding (shares)	23,611,680	22,419,417