Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Supplemental non-cash investing and financing activities:
Value of common stock issued in payment of accrued liability	$ 188	$ 0
Exercise of stock options by common stock surrender	5,814	0
Supplemental cash payment information:
Interest paid	1,069	921
Income taxes received, net of payments (paid, net of refunds)	$ 9,489	$ (3,429)