Derivative and Hedging Activities - Derivatives Subject to a Master Netting Arrangement (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Derivatives designated hedging instruments: | Interest rate swaps on FHLB advances
Liabilities
Gross Amount	$ 1	$ 5
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	1	5
Financial Instruments	0	4
Cash Collateral Pledged (Received)	92	27
Derivatives designated hedging instruments: | Interest rate swaps on multi-family loans held for investment
Liabilities
Gross Amount	0
Gross Amounts Netted in the Statements of Condition	0
Net Amount Presented in the Statements of Condition	0
Financial Instruments	0
Cash Collateral Pledged (Received)	34
Derivatives not designated as hedging instruments:
Assets
Gross Amount	160	220
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	160	220
Financial Instruments	0	0
Cash Collateral Pledged (Received)	(19)	(44)
Liabilities
Gross Amount	68	126
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	68	126
Financial Instruments	0	0
Cash Collateral Pledged (Received)	32	83
Derivatives not designated as hedging instruments: | Mortgage-backed securities forwards
Assets
Gross Amount	21	36
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	21	36
Financial Instruments	0	0
Cash Collateral Pledged (Received)	(4)	(9)
Liabilities
Gross Amount	7	61
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	7	61
Financial Instruments	0	0
Cash Collateral Pledged (Received)	6	54
Derivatives not designated as hedging instruments: | Interest rate swaptions
Assets
Gross Amount	136	182
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	136	182
Financial Instruments	0	0
Cash Collateral Pledged (Received)	(15)	(36)
Derivatives not designated as hedging instruments: | Futures
Assets
Gross Amount	3	2
Gross Amounts Netted in the Statements of Condition	0
Net Amount Presented in the Statements of Condition	3	2
Financial Instruments	0
Cash Collateral Pledged (Received)	0	1
Liabilities
Gross Amount	0
Gross Amounts Netted in the Statements of Condition	0
Net Amount Presented in the Statements of Condition	0
Financial Instruments	0
Cash Collateral Pledged (Received)	0
Derivatives not designated as hedging instruments: | Interest rate swaps
Liabilities
Gross Amount	61	65
Gross Amounts Netted in the Statements of Condition	0	0
Net Amount Presented in the Statements of Condition	61	65
Financial Instruments	0	0
Cash Collateral Pledged (Received)	$ 26	$ 29