Loans and Leases - Summary of Consumer Loans by Payment Status (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Credit Quality [Line Items]
Total Loans	$ 14,563,128	$ 12,190,440
Performing [Member]
Credit Quality [Line Items]
Performing Loans	5,104,618	4,731,813
Non Performing Consumer Originated [Member]
Credit Quality [Line Items]
Non-Performing Loans	33,032	30,116
Direct Installment [Member]
Credit Quality [Line Items]
Total Loans	1,830,206	1,706,636
Direct Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Performing Loans	1,718,741	1,646,925
Direct Installment [Member] | Non Performing Consumer Originated [Member]
Credit Quality [Line Items]
Non-Performing Loans	14,865	13,792
Residential Mortgages [Member]
Credit Quality [Line Items]
Total Loans	1,678,646	1,395,971
Residential Mortgages [Member] | Performing [Member]
Credit Quality [Line Items]
Performing Loans	1,204,189	1,031,926
Residential Mortgages [Member] | Non Performing Consumer Originated [Member]
Credit Quality [Line Items]
Non-Performing Loans	13,385	12,763
Indirect Installment [Member]
Credit Quality [Line Items]
Total Loans	1,076,817	996,729
Indirect Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Performing Loans	1,074,744	994,661
Indirect Installment [Member] | Non Performing Consumer Originated [Member]
Credit Quality [Line Items]
Non-Performing Loans	1,772	1,514
Consumer Lines of Credit [Member] | Performing [Member]
Credit Quality [Line Items]
Performing Loans	1,055,118	1,019,783
Consumer Lines of Credit [Member] | Non Performing Consumer Originated [Member]
Credit Quality [Line Items]
Non-Performing Loans	3,010	2,047
Other [Member]
Credit Quality [Line Items]
Total Loans	51,826	38,518
Other [Member] | Performing [Member]
Credit Quality [Line Items]
Performing Loans	51,826	38,518
Originated Consumer Loans [Member]
Credit Quality [Line Items]
Total Loans	5,137,650	4,761,929
Originated Consumer Loans [Member] | Direct Installment [Member]
Credit Quality [Line Items]
Total Loans	1,733,606	1,660,717
Originated Consumer Loans [Member] | Residential Mortgages [Member]
Credit Quality [Line Items]
Total Loans	1,217,574	1,044,689
Originated Consumer Loans [Member] | Indirect Installment [Member]
Credit Quality [Line Items]
Total Loans	1,076,516	996,175
Originated Consumer Loans [Member] | Consumer Lines of Credit [Member]
Credit Quality [Line Items]
Total Loans	1,058,128	1,021,830
Originated Consumer Loans [Member] | Other [Member]
Credit Quality [Line Items]
Total Loans	$ 51,826	$ 38,518