RESTRICTED CASH - Schedule of Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 431,806	$ 84,507	$ 78,151
Total cash, cash equivalents and restricted cash shown in the Consolidated Statements of Cash Flows	481,640	87,482	78,626	$ 69,968
Timber Funds
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	12,202	4,053
Restricted cash, Timber Funds	49,209	0	0
Excluding Timber Funds
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	419,604	80,454
RESTRICTED CASH, EXCLUDING TIMBER FUNDS	$ 625	$ 2,975	$ 475