Credit Risk Profile Based on Payment Activity - Originated and Non-PCI Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	$ 8,916,128	$ 7,465,794	$ 6,920,683
Commercial - credit card [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	126,526	115,709
Commercial - credit card [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	126,526	115,709
Commercial - credit card [Member] | Performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	126,501	115,672
Commercial - credit card [Member] | Non-performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	25	37
Real estate - residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	433,287	319,827
Real estate - residential [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	433,287	319,827
Real estate - residential [Member] | Performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	431,037	319,265
Real estate - residential [Member] | Non-performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	2,250	562
Real estate - HELOC [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	698,814	643,586
Real estate - HELOC [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	698,767	643,586
Real estate - HELOC [Member] | Performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	694,769	643,567
Real estate - HELOC [Member] | Non-performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	3,998	19
Consumer - credit card [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	286,478	310,296
Consumer - credit card [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	286,478	310,296
Consumer - credit card [Member] | Performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	285,799	309,736
Consumer - credit card [Member] | Non-performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	679	560
Consumer - other [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	94,460	100,970
Consumer - other [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	91,771	100,970
Consumer - other [Member] | Performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	90,485	100,900
Consumer - other [Member] | Non-performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	1,286	70
Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	40,073	39,090	$ 23,793
Leases [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	40,073	39,090
Leases [Member] | Performing [Member] | Originated and Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit Risk Profile Based on Payment Activity	$ 40,073	$ 39,090