Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Supplemental non-cash investing and financing activities:
Value of common stock issued in payment of accrued liability	$ 0	$ 188
Exercise of stock options by common stock surrender	0	7
Supplemental cash payment information:
Interest paid	457	553
Income taxes paid, net of refunds (received, net of payments)	$ 71	$ (114)