Variable Interest Entities - Variable Interest Entities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Variable Interest Entity [Line Items]
AFS investment securities	$ 1,154,021	$ 1,140,071
Accrued expenses and other liabilities	190,551	216,596
Other assets	341,838	368,996
Assets	18,813,181	19,026,645
Liabilities	15,910,380	16,144,064
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Maximum Loss	149,344	153,214
Assets	132,928	137,289
Liabilities	31,492	32,415
Variable Interest Entity, Not Primary Beneficiary | Multifamily Loan Securitization, Asset
Variable Interest Entity [Line Items]
Maximum Loss	47,443	48,204
AFS investment securities	47,443	48,204
Variable Interest Entity, Not Primary Beneficiary | Multifamily Loan Securitization, Liability
Variable Interest Entity [Line Items]
Maximum Loss	47,563	47,994
Accrued expenses and other liabilities	345	345
Variable Interest Entity, Not Primary Beneficiary | Affordable Housing Partnership, Asset
Variable Interest Entity [Line Items]
Maximum Loss	54,338	57,016
Other assets	85,485	89,085
Variable Interest Entity, Not Primary Beneficiary | Affordable Housing Partnership, Liability
Variable Interest Entity [Line Items]
Maximum Loss	0	0
Accrued expenses and other liabilities	$ 31,147	$ 32,070