DEBT - Revolving Credit Facility (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) fiscalQuarter equityCureRight	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Sep. 17, 2021 USD ($)
Debt Instrument [Line Items]
Borrowings on mortgage warehouse facilities	$ 562,024,000	$ 697,398,000
Letters of credit utilized	1,200,000,000		$ 1,200,000,000
Revolving credit facility borrowings	0		31,529,000
Revolving Credit Facility | $800 Million Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity on line of credit	800,000,000
Borrowings on mortgage warehouse facilities	0		0
Unamortized debt issuance costs	3,200,000		1,100,000
Letters of credit utilized	52,900,000		58,700,000
Line of credit available	$ 747,100,000		741,300,000
Maximum capitalization ratio	60.00%
Minimum net worth required	$ 2,500,000,000
Revolving credit facility borrowings	$ 40,000,000
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	$ 100,000,000			$ 100,000,000
Borrowings on mortgage warehouse facilities	0		31,500,000
Unamortized debt issuance costs	600,000		700,000
Letters of credit utilized	0
Line of credit available	$ 100,000,000		$ 68,500,000
Maximum capitalization ratio	60.00%
Minimum net worth required	$ 2,500,000,000
Revolving credit facility borrowings	$ 40,000,000
Maximum consecutive days for financial covenant	5 days
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