NOTES PAYABLE - DIRECT CORPORATE OBLIGATIONS - NARRATIVE (Details) - USD ($)	Jul. 16, 2021	Sep. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Outstanding amount		$ 1,138,400,000	$ 1,137,300,000
Line of Credit | Revolving Credit Agreement
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity	$ 250,000,000
Total capitalization percentage	15.00%
Debt covenant, required minimum debt to total capitalization ratio	35.00%
Debt covenant, actual debt to total capitalization ratio at period end		22.00%
Debt covenant, minimum required consolidated net worth, component one, amount	$ 2,674,000,000
Debt covenant, minimum required consolidated net worth, component two, as a percent of net equity proceeds received from issuance and sale of equity interests	25.00%
Debt covenant, actual consolidated net worth at period end		$ 3,463,600,000
Debt covenant, required minimum consolidated net worth, amount		2,692,700,000
Outstanding amount		$ 0	$ 0
Line of Credit | Revolving Credit Agreement | Eurodollar | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	1.375%
Line of Credit | Revolving Credit Agreement | Eurodollar | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	2.125%
Line of Credit | Revolving Credit Agreement | Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.375%
Line of Credit | Revolving Credit Agreement | Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	1.125%