Financial Guarantee Liability - Narrative (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($) loan	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) loan	Dec. 31, 2022 USD ($)
Guarantor Obligations
Outstanding loan balances	$ 29,800,000		$ 29,100,000
Maximum loss potential	9,200,000		9,000,000
Provision (reversal) for expected credit losses	$ 1,251	$ 2,800	2,634
Delinquency threshold period	60 days
Financial guarantee liability, settlement loss				$ 1,200
Financial guarantee liability, settlement loss, write off				$ 600
Delinquent
Guarantor Obligations
Outstanding loan balances	$ 7,300		7,300
Maximum loss potential	$ 2,400		2,400
Number of loans | loan	1
Liquidation value of loans outstanding	$ 7,400		7,500
Potential loss on liquidation of loan	$ 500		$ 500
Foreclosure
Guarantor Obligations
Number of loans | loan			1
Fannie Mae DUS or Freddie TAH Loans | Maximum
Guarantor Obligations
Percentage of contingent liability of actual losses incurred on outstanding loans	33.00%