Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental disclosures:
Interest paid	$ 0	$ 6	$ 0
Income taxes paid, net	2,172	14,979	16,951
Non-cash investing and financing activities:
Non-cash capital expenditures	$ 863	$ 481	$ 832