Derivative and Hedging Activities - Derivatives Subject to a Master Netting Arrangement (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Derivatives designated hedging instruments: | Interest rate swap on FHLB advances
Liabilities
Gross Amount	$ 7	$ 5
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	7	5
Financial Instruments	0	4
Cash Collateral Pledged (Received)	96	27
Derivatives designated hedging instruments: | Interest rate swap on multi-family loans held for investment
Liabilities
Gross Amount	2
Gross Amounts Netted in the Statements of Condition	0
Net Amount Presented in the Statements of Condition	2
Financial Instruments	0
Cash Collateral Pledged (Received)	35
Derivatives not designated as hedging instruments:
Assets
Gross Amount	164	220
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	164	220
Financial Instruments	0	0
Cash Collateral Pledged (Received)	(27)	(44)
Liabilities
Gross Amount	64	126
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	64	126
Financial Instruments	0	0
Cash Collateral Pledged (Received)	55	83
Derivatives not designated as hedging instruments: | Mortgage-backed securities forwards
Assets
Gross Amount	5	36
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	5	36
Financial Instruments	0	0
Cash Collateral Pledged (Received)	(3)	(9)
Liabilities
Gross Amount	14	61
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	14	61
Financial Instruments	0	0
Cash Collateral Pledged (Received)	8	54
Derivatives not designated as hedging instruments: | Interest rate swaptions
Assets
Gross Amount	159	182
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	159	182
Financial Instruments	0	0
Cash Collateral Pledged (Received)	(24)	(36)
Derivatives not designated as hedging instruments: | Futures
Assets
Gross Amount	0	2
Gross Amounts Netted in the Statements of Condition	0
Net Amount Presented in the Statements of Condition	0	2
Financial Instruments	0
Cash Collateral Pledged (Received)	0	1
Liabilities
Gross Amount	1
Gross Amounts Netted in the Statements of Condition	0
Net Amount Presented in the Statements of Condition	1
Financial Instruments	0
Cash Collateral Pledged (Received)	3
Derivatives not designated as hedging instruments: | Interest rate swaps
Liabilities
Gross Amount	49	65
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	49	65
Financial Instruments	0	0
Cash Collateral Pledged (Received)	$ 44	$ 29