Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental disclosures:
Interest paid	$ 0	$ 0	$ 1
Income taxes paid, net	24,125	26,456	19,884
Non-cash investing and financing activities:
Non-cash capital expenditures	83	(79)	71
Trade-in of equipment	$ 0	$ 0	$ 315