Loans and Leases - Concentrations and Restrictions (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 59,706,531	$ 31,061,111
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	33,655,717	20,051,091
Commercial | Commercial, Financial, and Industrial (a)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 28,048,649	15,640,208
Commercial | Commercial, Financial, and Industrial (a) | Finance And Insurance Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage contributed in total loan	5.00%
Loans, net of unearned income	$ 3,100,000
Percentage of commercial & industrial loan portfolio	9.00%
Commercial | Commercial, Financial, and Industrial (a) | Loans to mortgage companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage contributed in total loan	9.00%
Loans, net of unearned income	$ 5,607,068	4,410,883
Percentage of commercial & industrial loan portfolio	17.00%
Percentage Contributed	26.00%
Commercial | Loans to mortgage companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 5,607,068	$ 4,410,883
Residential Portfolio Segment [Member] | Real Estate Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage contributed in total loan	21.00%