DEBT - Revolving Credit Facility (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2022 USD ($) fiscalQuarter equityCureRight	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Long-term debt, gross	$ 2,962,635	$ 3,299,802
Letters of credit utilized	1,200,000	1,200,000
Revolving credit facility borrowings	150,000	31,529
Revolving Credit Facility | $800 Million Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity on line of credit	800,000
Long-term debt, gross	150,000	0
Unamortized debt issuance costs	3,000	1,100
Letters of credit utilized	66,300	58,700
Line of credit available	$ 583,700	741,300
Maximum capitalization ratio	60.00%
Minimum net worth required	$ 2,500,000
Revolving credit facility borrowings	$ 40,000
Number of consecutive fiscal quarters in which equity cure right can be used twice (in fiscal quarter) | fiscalQuarter	4
Maximum number of times equity cure right can be exercised | equityCureRight	5
Revolving Credit Facility | $100 Million Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity on line of credit	$ 100,000
Long-term debt, gross	$ 0	$ 31,529
Maximum consecutive days for financial covenant	5 days