Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental disclosures:
Interest paid	$ 0	$ 0	$ 6
Income taxes paid, net	13,754	2,172	14,979
Non-cash investing and financing activities:
Non-cash capital expenditures	$ 2,843	$ 863	$ 481