Other Debt - Summary of Maximum Borrowing Capacity and Current Gross Balances Outstanding (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022	Apr. 16, 2021	Jan. 29, 2021	Sep. 12, 2018
Debt Instrument [Line Items]
Period end balance	$ 237,025,000	$ 331,740,000
Maximum borrowing capacity	813,000,000	831,818,000
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	3,000,000	3,000,000			$ 50,000,000.0
2021 Term Repurchase Agreement | Secured Debt
Debt Instrument [Line Items]
Period end balance	73,097,000	74,334,000
Maximum borrowing capacity	100,000,000	100,000,000	$ 100,000,000.0
2021 Repurchase Agreement | Secured Debt
Debt Instrument [Line Items]
Period end balance	54,482,000	79,504,000
Maximum borrowing capacity	200,000,000	200,000,000		$ 200,000,000.0
July 2021 Term Repurchase Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	100,000,000.0
July 2021 Term Repurchase Agreement | Secured Debt
Debt Instrument [Line Items]
Period end balance	8,534,000	2,185,000
Maximum borrowing capacity	100,000,000	100,000,000
2013 Repurchase Agreement | Secured Debt
Debt Instrument [Line Items]
Period end balance	69,436,000	136,165,000
Maximum borrowing capacity	300,000,000.0	300,000,000
Bank Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Period end balance	31,476,000	29,495,000
Maximum borrowing capacity	50,000,000	50,000,000
October 2022 Repurchase Agreement | Secured Debt
Debt Instrument [Line Items]
Period end balance		10,057,000
Maximum borrowing capacity		18,818,000
September 2022 Term Repurchase Agreement | Secured Debt
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 60,000,000	$ 60,000,000