v3.26.1
FINANCIAL DERIVATIVES - Schedule of Derivative Instruments in Statement of Financial Position (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Dec. 31, 2025
Notional Disclosures [Abstract]    
Notional Amount $ 26,583,605 $ 25,577,094
Asset    
Fair value, asset 15,481 44,875
Netting adjustments (2,625) (1,631)
(Liability)    
Fair value, liability (46,490) (21,618)
Netting adjustments 2,625 1,631
Receive fixed non-callable | No hedge designation    
Notional Disclosures [Abstract]    
Notional Amount 1,639,902 1,963,363
Asset    
Fair value, asset 125 66
(Liability)    
Fair value, liability $ (1) $ (9)
Weighted- Average Pay Rate 3.72% 3.89%
Weighted- Average Receive Rate 3.83% 3.93%
Weighted- Average Remaining Term (in years) 4 months 6 days 3 months 10 days
Receive fixed non-callable | Fair value hedges: | Designated as hedge    
Notional Disclosures [Abstract]    
Notional Amount $ 6,235,735 $ 10,681,418
Asset    
Fair value, asset 1,608 16,685
(Liability)    
Fair value, liability $ (1,118) $ (168)
Weighted- Average Pay Rate 3.89% 2.79%
Weighted- Average Receive Rate 3.54% 3.93%
Weighted- Average Remaining Term (in years) 1 year 8 years 7 months 28 days
Pay fixed non-callable | No hedge designation    
Notional Disclosures [Abstract]    
Notional Amount $ 153,384 $ 159,684
Asset    
Fair value, asset 448 613
(Liability)    
Fair value, liability $ (80) $ (1)
Weighted- Average Pay Rate 2.89% 2.88%
Weighted- Average Receive Rate 3.94% 4.13%
Weighted- Average Remaining Term (in years) 3 years 6 months 3 years 7 months 9 days
Pay fixed non-callable | Fair value hedges: | Designated as hedge    
Notional Disclosures [Abstract]    
Notional Amount $ 11,068,510 $ 6,388,935
Asset    
Fair value, asset 880 330
(Liability)    
Fair value, liability $ (6,843) $ (2,954)
Weighted- Average Pay Rate 2.84% 4.08%
Weighted- Average Receive Rate 3.73% 3.56%
Weighted- Average Remaining Term (in years) 8 years 5 months 4 days 1 year 1 month 13 days
Pay fixed non-callable | Cash flow hedges: | Designated as hedge    
Notional Disclosures [Abstract]    
Notional Amount $ 440,000 $ 452,000
Asset    
Fair value, asset 8,723 9,335
(Liability)    
Fair value, liability $ (197) $ (1)
Weighted- Average Pay Rate 1.90% 1.92%
Weighted- Average Receive Rate 4.12% 4.22%
Weighted- Average Remaining Term (in years) 2 years 10 months 2 days 3 years
Receive fixed callable | Fair value hedges: | Designated as hedge    
Notional Disclosures [Abstract]    
Notional Amount $ 6,602,663 $ 5,446,883
Asset    
Fair value, asset 6,018 19,322
(Liability)    
Fair value, liability $ (40,619) $ (19,911)
Weighted- Average Pay Rate 3.77% 3.96%
Weighted- Average Receive Rate 3.84% 3.73%
Weighted- Average Remaining Term (in years) 3 years 5 months 19 days 3 years 1 month 20 days
Basis swaps | No hedge designation    
Notional Disclosures [Abstract]    
Notional Amount $ 382,811 $ 382,811
Asset    
Fair value, asset 0 1
(Liability)    
Fair value, liability $ (164) $ (190)
Weighted- Average Pay Rate 3.94% 4.13%
Weighted- Average Receive Rate 3.86% 3.89%
Weighted- Average Remaining Term (in years) 4 years 9 months 10 days 5 years 10 days
Treasury futures | No hedge designation    
Notional Disclosures [Abstract]    
Notional Amount $ 60,600 $ 102,000
Asset    
Fair value, asset 304 154
Netting adjustments (2,625) (1,631)
(Liability)    
Fair value, liability (93) (15)
Netting adjustments $ 2,625 $ 1,631
Weighted- Average Forward Price (in dollars per share) $ 111.40 $ 112.57