Loans and Allowance for Credit Losses on Loans - Amortized cost basis and ACL (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	$ 8,627,048	$ 7,470,872
Allowance for credit losses on loans	51,838	44,014	$ 32,102
Collateral Dependent Loans
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	65,414
Allowance for credit losses on loans	1,736
Real Estate
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	58,921
Accounts Receivable Or Equipment
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	4,986
Other Collateralized Assets
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	1,507
Mortgage warehouse lines of credit
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	604,445	464,785
Allowance for credit losses on loans	1,664	1,249	1,941
Residential real estate
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	1,215,252	1,178,401
Allowance for credit losses on loans	7,378	7,029	4,547
Residential real estate | Collateral Dependent Loans
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	240
Allowance for credit losses on loans	38
Residential real estate | Real Estate
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	231
Residential real estate | Other Collateralized Assets
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	9
Multi-family financing
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	3,566,530	3,135,535
Allowance for credit losses on loans	19,851	16,781	15,131
Multi-family financing | Collateral Dependent Loans
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	36,760
Allowance for credit losses on loans	184
Multi-family financing | Real Estate
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	36,760
Healthcare financing
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	1,941,204	1,604,341
Allowance for credit losses on loans	11,753	9,882	5,618
Healthcare financing | Collateral Dependent Loans
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	21,783
Allowance for credit losses on loans	132
Healthcare financing | Real Estate
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	21,783
Commercial and commercial real estate
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	1,194,320	978,661
Allowance for credit losses on loans	10,482	8,326	4,102
Commercial and commercial real estate | Collateral Dependent Loans
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	6,479
Allowance for credit losses on loans	1,381
Commercial and commercial real estate | Accounts Receivable Or Equipment
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	4,986
Commercial and commercial real estate | Other Collateralized Assets
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	1,493
Agricultural production and real estate
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	89,516	95,651
Allowance for credit losses on loans	543	565	597
Agricultural production and real estate | Collateral Dependent Loans
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	147
Allowance for credit losses on loans	1
Agricultural production and real estate | Real Estate
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	147
Consumer and margin loans
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	15,781	13,498
Allowance for credit losses on loans	167	$ 182	$ 166
Consumer and margin loans | Collateral Dependent Loans
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	5
Consumer and margin loans | Other Collateralized Assets
Loans and Allowance for Credit Losses on Loans
Amortized Cost Basis	$ 5