v3.26.3
Loans and the Allowance for Credit Losses - Summary of Commercial Loans by Risk Grade (Detail) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income $ 19,900,551 $ 19,226,432
Commercial and Industrial [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 3,067,867 2,863,893
Commercial and Industrial [Member] | Pass [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 2,895,883 2,736,863
Commercial and Industrial [Member] | Criticized [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 87,086 84,552
Commercial and Industrial [Member] | Classified - substandard [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 84,898 42,478
Commercial Portfolio Segment [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 14,387,382 13,802,727
Commercial Portfolio Segment [Member] | Pass [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 13,752,297 13,197,799
Commercial Portfolio Segment [Member] | Criticized [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 330,433 413,068
Commercial Portfolio Segment [Member] | Classified - substandard [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 304,652 191,860
Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 1,637,322 1,783,637
Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member] | Pass [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 1,578,258 1,748,260
Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member] | Criticized [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 29,529 8,331
Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member] | Classified - substandard [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 29,535 27,046
Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 9,682,193 9,155,197
Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member] | Pass [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 9,278,156 8,712,676
Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member] | Criticized [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 213,818 320,185
Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member] | Classified - substandard [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 190,219 122,336
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 3,067,867 2,863,893
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Pass [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 2,895,883 2,736,863
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Criticized [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income 87,086 84,552
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Classified - substandard [Member]    
Summary of commercial loans by risk grade    
Portfolio loans, net of unearned income $ 84,898 $ 42,478