Loans and Allowance for Credit Losses - Credit Risk Profile Based on Payment Activity (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	$ 15,305,097	$ 13,431,722	$ 12,900,269
Leases Portfolio [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		1,978	$ 4,733
Originated and Non-PCI Loans [Member] | Leases Portfolio [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		1,978
Originated and Non-PCI Loans [Member] | Performing [Member] | Leases Portfolio [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		1,978
Commercial Credit Card [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		182,238
Commercial Credit Card [Member] | Originated and Non-PCI Loans [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		182,214
Commercial Credit Card [Member] | Originated and Non-PCI Loans [Member] | Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		24
Real Estate Residential [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		933,276
Real Estate Residential [Member] | Originated and Non-PCI Loans [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		926,312
Real Estate Residential [Member] | Originated and Non-PCI Loans [Member] | Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		6,964
Real Estate HELOC [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		478,151
Real Estate HELOC [Member] | Originated and Non-PCI Loans [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		468,228
Real Estate HELOC [Member] | Originated and Non-PCI Loans [Member] | Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		9,923
Consumer Credit Card [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		226,742
Consumer Credit Card [Member] | Originated and Non-PCI Loans [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		225,939
Consumer Credit Card [Member] | Originated and Non-PCI Loans [Member] | Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		803
Consumer Other [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		133,474
Consumer Other [Member] | Originated and Non-PCI Loans [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		132,414
Consumer Other [Member] | Originated and Non-PCI Loans [Member] | Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity		$ 1,060