Loans Held for Investment and the Allowance for Credit Losses - Summary of Amortized Cost and Results of Internal Risk Rating Review Performed for Loans Held for Investment Portfolio (Details) $ in Thousands	Mar. 31, 2022 USD ($) Ratings	Dec. 31, 2021 USD ($)	Dec. 31, 2021 Ratings	Dec. 31, 2021 Rate
Accounts Notes And Loans Receivable [Line Items]
Carrying Value, Gross	$ 5,115,788	$ 4,909,202
Allowance for credit losses	(46,307)	(41,999)
Carrying value	$ 5,069,481	4,867,203
Weighted Average Risk Rating	3.1		3.0	3.0
Rating 2
Accounts Notes And Loans Receivable [Line Items]
Carrying Value, Gross	$ 543,401	527,051
Rating 3
Accounts Notes And Loans Receivable [Line Items]
Carrying Value, Gross	3,360,840	3,726,753
Rating 4
Accounts Notes And Loans Receivable [Line Items]
Carrying Value, Gross	1,188,547	632,398
Rating 5
Accounts Notes And Loans Receivable [Line Items]
Carrying Value, Gross	$ 23,000	$ 23,000