Derivatives and Hedging Activities (Net gains (losses) on fair value and cash flow hedges) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Derivative Instruments, Gain (Loss) [Line Items]
Advances	$ 530,708	$ 768,217
Available-for-sale securities	215,764	252,746
Interest Expense, Other Long-term Debt	(557,767)	(934,377)
Interest Expense, Other Short-term Borrowings	(315,092)	(180,870)
Total other comprehensive income (loss)	944	(13,552)
Unrealized gains (losses) on cash flow hedges	4,358	(7,746)
Interest Rate Contract [Member] \| Designated as Hedging Instrument [Member] \| Other Comprehensive Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	(3,395)	(5,732)
Unrealized gains (losses) on cash flow hedges	4,358	(7,746)
Net Gain (Loss) on Cash Flow Hedging Relationship	963	(13,478)
Advances [Member] \| Interest Rate Contract [Member] \| Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	96,130	(124,786)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	(66,509)	191,790
Gain (Loss) on Fair Value Hedges Recognized in Earnings	29,621	67,004
Categories of Investments, Marketable Securities, Available-for-sale Securities [Member] \| Interest Rate Contract [Member] \| Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	93,657	(238,429)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	(60,613)	312,607
Gain (Loss) on Fair Value Hedges Recognized in Earnings	33,044	74,178
Consolidated Obligation Bonds [Member] \| Interest Rate Contract [Member] \| Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(82,786)	125,546
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	13,403	(257,878)
Gain (Loss) on Fair Value Hedges Recognized in Earnings	(69,383)	(132,332)
Consolidated Obligation Discount Notes [Member] \| Interest Rate Contract [Member] \| Interest Expense [Member] \| Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	3,395	5,732
Net Gain (Loss) on Cash Flow Hedging Relationship	$ 3,395	$ 5,732

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Amount of interest expense incurred on long-term debt classified as other, including, but not limited to, interest on long-term notes and amortization of issuance costs.

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