EMPLOYEE BENEFIT PLANS - Amounts Recognized in the Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Pension Benefits
Employee benefit plans
Net amount recognized	$ (60,511)	$ (59,148)
Pension Benefits | Noncurrent assets
Employee benefit plans
Net amount recognized	17,002	0
Pension Benefits | Accrued benefit costs
Employee benefit plans
Net amount recognized	282	104
Pension Benefits | Accrued benefit liability
Employee benefit plans
Net amount recognized	94,010	117,145
Pension Benefits | Regulatory assets (3)
Employee benefit plans
Net amount recognized	16,779	58,101
Pension Benefits | Other regulatory liabilities
Employee benefit plans
Net amount recognized	0	0
Other Benefits
Employee benefit plans
Net amount recognized	(623)	(2,368)
Other Benefits | Noncurrent assets
Employee benefit plans
Net amount recognized	26,966	16,399
Other Benefits | Accrued benefit costs
Employee benefit plans
Net amount recognized	1,124	1,782
Other Benefits | Accrued benefit liability
Employee benefit plans
Net amount recognized	0	0
Other Benefits | Regulatory assets (3)
Employee benefit plans
Net amount recognized	829	1,487
Other Benefits | Other regulatory liabilities
Employee benefit plans
Net amount recognized	$ 27,294	$ 18,472