Unaudited Condensed Consolidated Statements of Cash Flows - Supplemental - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Supplemental disclosures:
Cash and cash equivalents	$ 266,372	$ 319,253
Restricted cash (Note 1)	109	106
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	266,481	319,359
Cash paid for income taxes, net of refunds	5,295	6,327
Non-cash transactions
Property and equipment purchases in accounts payable and accrued liabilities	571	430
Investment purchases in accounts payable, net	$ 0	$ 10,400