Borrowings - Repurchase agreements accounted for as secured borrowings (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	$ 93,071	$ 148,609
Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	93,071	148,609
US Treasury Securities | Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	44,115	48,670
US Treasury Securities | Within 30 days | Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	12,736	410
US Treasury Securities | After 30 to 90 days | Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	13,199	30,739
US Treasury Securities | After 90 days | Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	18,180	17,521
Mortgage Backed Securities | Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	48,710	99,775
Mortgage Backed Securities | Within 30 days | Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	28,211	98,984
Mortgage Backed Securities | After 30 to 90 days | Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	0	791
Mortgage Backed Securities | After 90 days | Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	20,499	0
CMO | Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	246	164
CMO | Within 30 days | Secured Debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase liability	$ 246	$ 164