Financial Guarantee Liability - Narrative (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) loan	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) loan
Guarantor Obligations
Outstanding loan balances	$ 26,100,000		$ 25,800,000
Maximum loss potential	7,900,000		7,800,000
Provision for expected credit losses	195	$ (1,600)	(3,592)
Delinquent
Guarantor Obligations
Outstanding loan balances	10,700		33,600
Maximum loss potential	$ 3,600		$ 11,200
Number of loans | loan	1		2
Liquidation value of loans outstanding	$ 10,600		$ 28,400
Potential loss on liquidation of loan	100	$ 2,300
Foreclosure
Guarantor Obligations
Outstanding loan balances			$ 22,800
Maximum loss potential	$ 7,600
Number of loans | loan	1
Liquidation value of loans outstanding	$ 19,900
Potential loss on liquidation of loan	$ 1,100
Fannie Mae DUS or Freddie TAH Loans | Maximum
Guarantor Obligations
Percentage of contingent liability of actual losses incurred on outstanding loans	33.00%