DEBT - Credit Agreement (Details) - Line of credit - Unsecured revolving credit agreement	3 Months Ended
	Mar. 31, 2021 USD ($)
Revolving credit facility
Line of Credit Facility [Line Items]
Debt instrument term (in years)	5 years
Maximum borrowing capacity	$ 2,000,000,000.0
Facility fee (percent)	0.15%
Debt to capitalization percentage, maximum	50.00%
Actual debt to capitalization percentage	34.00%
Maximum borrowing capacity including uncommitted incremental loan facility	$ 2,500,000,000
Uncommitted incremental loan facility	500,000,000
Line of credit, outstanding borrowings	0
Remaining borrowing capacity	$ 2,000,000,000.0
Revolving credit facility | Minimum
Line of Credit Facility [Line Items]
Facility fee (percent)	0.09%
Revolving credit facility | Maximum
Line of Credit Facility [Line Items]
Facility fee (percent)	0.25%
Revolving credit facility | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)	1.10%
Revolving credit facility | LIBOR | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)	0.91%
Revolving credit facility | LIBOR | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)	1.50%
Letter of credit
Line of Credit Facility [Line Items]
Line of credit, outstanding borrowings	$ 0