DEBT - Revolving Credit Agreements (Details) - USD ($)	1 Months Ended	3 Months Ended
	Jun. 30, 2021	Sep. 30, 2021
Revolving credit facility
Line of Credit Facility [Line Items]
Debt to capitalization percentage, maximum		60.00%
Actual debt to capitalization percentage		43.00%
Uncommitted incremental loan facility		$ 750,000,000
Maximum borrowing capacity including uncommitted incremental loan facility		4,750,000,000
Outstanding borrowings		$ 0
Revolving credit facility | 5-year unsecured revolving credit agreement
Line of Credit Facility [Line Items]
Debt instrument term (in years)	5 years	5 years
Maximum borrowing capacity	$ 2,500,000,000
Facility fee (percent)		0.15%
Remaining borrowing capacity		$ 2,500,000,000
Revolving credit facility | 5-year unsecured revolving credit agreement | Minimum
Line of Credit Facility [Line Items]
Facility fee (percent)		0.09%
Revolving credit facility | 5-year unsecured revolving credit agreement | Maximum
Line of Credit Facility [Line Items]
Facility fee (percent)		0.225%
Revolving credit facility | 5-year unsecured revolving credit agreement | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)		1.10%
Revolving credit facility | 5-year unsecured revolving credit agreement | LIBOR | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)		0.91%
Revolving credit facility | 5-year unsecured revolving credit agreement | LIBOR | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)		1.40%
Revolving credit facility | 364-day unsecured revolving credit agreement
Line of Credit Facility [Line Items]
Debt instrument term (in years)	364 days	364 days
Maximum borrowing capacity	$ 1,500,000,000
Facility fee (percent)		0.10%
Remaining borrowing capacity		$ 1,500,000,000
Revolving credit facility | 364-day unsecured revolving credit agreement | Minimum
Line of Credit Facility [Line Items]
Facility fee (percent)		0.07%
Revolving credit facility | 364-day unsecured revolving credit agreement | Maximum
Line of Credit Facility [Line Items]
Facility fee (percent)		0.175%
Revolving credit facility | 364-day unsecured revolving credit agreement | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)		1.15%
Revolving credit facility | 364-day unsecured revolving credit agreement | LIBOR | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)		0.93%
Revolving credit facility | 364-day unsecured revolving credit agreement | LIBOR | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)		1.45%
Letter of credit
Line of Credit Facility [Line Items]
Outstanding borrowings		$ 1,000,000