Other Debt - Summary of Maximum Borrowing Capacity and Current Gross Balances Outstanding (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021	Apr. 16, 2021	Jan. 29, 2021	Sep. 12, 2018
Debt Instrument [Line Items]
Period end balance	$ 341,412,000	$ 302,800,000
Maximum borrowing capacity	810,000,000	653,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 50,000,000.0
2021 Term Repurchase Agreement | Secured Debt
Debt Instrument [Line Items]
Period end balance	47,777,000	41,636,000
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	93,915,000	82,580,000
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	1,632,000
Maximum borrowing capacity	100,000,000	100,000,000
2013 Repurchase Agreement | Secured Debt
Debt Instrument [Line Items]
Period end balance	138,776,000	153,499,000
Maximum borrowing capacity	300,000,000.0	200,000,000
Bank Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Period end balance	43,120,000	22,385,000
Maximum borrowing capacity	50,000,000	50,000,000
2019 Term Loan | Secured Debt
Debt Instrument [Line Items]
Period end balance		2,700,000
Maximum borrowing capacity		$ 3,000,000
2011 Facility Agreement | Secured Debt
Debt Instrument [Line Items]
Period end balance	16,192,000
Maximum borrowing capacity	$ 60,000,000