v3.26.3
Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments - Contractual Maturities and Estimated Fair Values (Details) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Amortized Cost          
Due in one year or less, held-to-maturity debt securities amortized cost $ 1,200,000   $ 1,200,000    
Due after one year through five years, held-to-maturity debt securities amortized cost 3,200,000   3,200,000    
Amortized cost, held-to-maturity debt securities 4,400,000   4,400,000   $ 4,400,000
Fair Value          
Due in one year or less, held-to-maturity debt securities, Estimated fair value 1,200,000   1,200,000    
Due after one year through five years, held-to-maturity debt securities, Estimated fair value 3,200,000   3,200,000    
Estimated fair value 4,400,000   4,400,000   4,400,000
Available-for-sale debt securities amortized cost disclosures          
Due after five years through ten years, available-for-sale debt securities amortized cost 2,865,000   2,865,000    
Due after ten years, available-for-sale debt securities amortized cost 134,252,000   134,252,000    
Residential mortgage-backed securities, available-for-sale debt securities amortized cost 5,498,264,000   5,498,264,000    
Amortized cost, Available-for-sale securities 5,635,381,000   5,635,381,000   5,281,090,000
Available for sale debt securities, Estimated Fair Value Disclosures          
Due after five years through ten years, available-for-sale debt securities, Estimated Fair Value 2,669,000   2,669,000    
Due after ten years, available-for-sale debt securities, Estimated Fair Value 115,242,000   115,242,000    
Residential mortgage-backed securities, available-for-sale debt securities, Estimated Fair Value 5,031,447,000   5,031,447,000    
Estimated fair value, Available for sale securities 5,149,358,000   5,149,358,000   $ 4,966,268,000
Available for sale debt securities, Estimated Fair Value Disclosures          
Proceeds from sales and calls of available for sale securities 480,000 $ 11,255,000 3,825,000 $ 15,490,000  
Proceeds from sales of mortgage-backed securities 0 0 0 0  
Gross gains realized on sales 0 0 0 0  
Gross losses realized on sales 0 $ 1,000 0 $ 1,000  
Collateral pledged          
Available-for-sale debt securities amortized cost disclosures          
Amortized cost, Available-for-sale securities 1,744,412,000   1,744,412,000    
Available for sale debt securities, Estimated Fair Value Disclosures          
Fair value of available for sale investment securities pledged $ 1,531,898,000   $ 1,531,898,000