Other Borrowings - Narrative (Details) $ in Millions		1 Months Ended	12 Months Ended	108 Months Ended
	Dec. 12, 2022	Dec. 31, 2014 CAD ($)	Dec. 31, 2023 USD ($) officeBuilding	Dec. 31, 2023 CAD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Sep. 18, 2018 USD ($)
Debt Instrument [Line Items]
Credit agreement balances			$ 171,282,000		$ 199,793,000
Other borrowings			59,204,000		61,267,000
Secured borrowings			401,897,000		317,942,000
Collateral Pledged
Debt Instrument [Line Items]
Pledged financial instruments			17,400,000
Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee	0.30%
Securities sold under repurchase agreements | Overnight Sweep Collateral
Debt Instrument [Line Items]
Securities sold under agreements to repurchase			13,400,000		17,600,000
Fixed Rate Promissory Note
Debt Instrument [Line Items]
Principal amount of debt			$ 66,400,000
Fixed interest rate			1.70%
Number of office buildings secured by debt | officeBuilding			3
Other borrowings			$ 59,200,000			$ 61,300,000
Secured Debt
Debt Instrument [Line Items]
Secured borrowings			9,400,000
Term Loan Facility
Debt Instrument [Line Items]
Credit agreement balances							$ 200,000,000
Amount outstanding			171,300,000
Revolving Credit Facility
Debt Instrument [Line Items]
Credit agreement balances							$ 100,000,000
Amount outstanding			0
Credit Agreement | Base rate | Base Rate Loan
Debt Instrument [Line Items]
Basis spread on variable rate	0.75%
Credit Agreement | Base rate | Term SOFR Loans
Debt Instrument [Line Items]
Basis spread on variable rate	1.60%
Credit Agreement | Federal funds rate | Base Rate Loan
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Credit Agreement | Secured Overnight Financing Rate (SOFR) | Base Rate Loan
Debt Instrument [Line Items]
Basis spread on variable rate	1.10%
Receivables Purchase Agreement | Secured Debt
Debt Instrument [Line Items]
Proceeds from debt issuance		$ 150		$ 520
Borrowing fee rate		0.775%		0.825%
Secured borrowings			$ 392,500,000		$ 309,700,000
Receivables Purchase Agreement | Canadian Commercial Paper Rate | Secured Debt
Debt Instrument [Line Items]
Basis spread on variable rate			0.825%