v3.26.1
Derivatives and Hedging Activities (Net gains (losses) on fair value and cash flow hedges) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]        
Advances $ 526,425 $ 790,229 $ 1,057,133 $ 1,558,446
Available-for-sale securities 209,347 250,510 425,111 503,256
Interest Expense, Other Long-term Debt (541,992) (961,280) (1,099,759) (1,895,657)
Interest Expense, Other Short-term Borrowings (302,340) (179,466) (617,432) (360,336)
Total other comprehensive income (loss) 61,264 (63,948) 62,208 (77,500)
Unrealized gains (losses) on cash flow hedges 5,177 (3,293) 9,535 (11,039)
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 (2,566) (5,977) (5,961) (11,709)
Unrealized gains (losses) on cash flow hedges 5,177 (3,293) 9,535 (11,039)
Net Gain (Loss) on Cash Flow Hedging Relationship 2,611 (9,270) 3,574 (22,748)
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 86,943 (21,798) 183,073 (146,584)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge (58,525) 98,213 (125,034) 290,003
Gain (Loss) on Fair Value Hedges Recognized in Earnings 28,418 76,415 58,039 143,419
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 176,853 (102,129) 270,510 (340,558)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge (149,102) 175,571 (209,715) 488,178
Gain (Loss) on Fair Value Hedges Recognized in Earnings 27,751 73,442 60,795 147,620
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 (60,094) 22,862 (142,880) 148,408
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge 16,145 (150,255) 29,548 (408,133)
Gain (Loss) on Fair Value Hedges Recognized in Earnings (43,949) (127,393) (113,332) (259,725)
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 2,566 5,977 5,961 11,709
Net Gain (Loss) on Cash Flow Hedging Relationship $ 2,566 $ 5,977 $ 5,961 $ 11,709