Derivative Instruments and Hedge Activities - Summary of Derivative Financial Instruments and Classification on Consolidated Statements of Financial Condition (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021
Derivatives Fair Value [Line Items]
Notional Amount	$ 945,414	$ 847,447
Other Assets	29,113	13,375
Other Liabilities	(7,475)	(9,665)
Cash Flow Hedging
Derivatives Fair Value [Line Items]
Notional Amount	450,000
Other Assets	21,782
Other Liabilities	0
Other Interest Rate Derivatives
Derivatives Fair Value [Line Items]
Notional Amount	488,064
Other Assets	7,331
Other Liabilities			$ (7,474)
Other Interest Rate Derivatives | Cash Flow Hedging
Derivatives Fair Value [Line Items]
Notional Amount	100,000
Derivatives Designated as Hedging Instruments | Interest Rate Swaps | Cash Flow Hedging
Derivatives Fair Value [Line Items]
Notional Amount	450,000	400,000
Other Assets	21,782	4,140
Other Liabilities	0	0
Derivatives Not Designated As Hedging Instruments | Other Credit Derivatives
Derivatives Fair Value [Line Items]
Notional Amount	7,350	7,571
Other Assets	0	0
Other Liabilities	1	5
Derivatives Not Designated As Hedging Instruments | Other Interest Rate Derivatives
Derivatives Fair Value [Line Items]
Notional Amount	488,064	439,876
Other Assets	7,331	9,235
Other Liabilities	$ 7,474	$ 9,660