LEASES - Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Right-of-use assets:
Operating lease right-of-use assets	$ 34,359	$ 37,030
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization
Finance lease right-of-use assets	$ 40,616	$ 47,549
Total right-of-use assets	74,975	84,579
Operating lease liabilities:
Current operating lease liabilities	11,230	11,613
Noncurrent operating lease liabilities	35,149	38,132
Total operating lease liabilities	$ 46,379	$ 49,745
Finance lease liabilities:
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accounts Payable and Accrued Liabilities, Current	Accounts Payable and Accrued Liabilities, Current
Current finance lease liabilities	$ 6,683	$ 6,227
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Noncurrent finance lease liabilities	$ 19,897	$ 25,027
Total finance lease liabilities	$ 26,580	$ 31,254