Loans and Leases - Summary of Commercial Loans by Credit Quality (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	$ 6,270,050	$ 5,407,427
Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	3,531,146	3,031,810
Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,534,351	2,197,793
Originated Loans and Leases [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	204,553	177,824
Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	645,281	904,120
Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	577,910	783,898
Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	67,371	120,222
Pass [Member] | Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	5,949,837	5,151,400
Pass [Member] | Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	3,416,527	2,890,830
Pass [Member] | Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,335,103	2,085,893
Pass [Member] | Originated Loans and Leases [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	198,207	174,677
Pass [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	520,608	714,122
Pass [Member] | Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	464,162	610,260
Pass [Member] | Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	56,446	103,862
Special Mention [Member] | Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	164,873	132,248
Special Mention [Member] | Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	52,887	58,630
Special Mention [Member] | Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	109,539	71,420
Special Mention [Member] | Originated Loans and Leases [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,447	2,198
Special Mention [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	50,801	77,397
Special Mention [Member] | Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	47,619	73,891
Special Mention [Member] | Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	3,182	3,506
Substandard [Member] | Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	152,690	122,584
Substandard [Member] | Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	61,411	81,951
Substandard [Member] | Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	87,380	39,684
Substandard [Member] | Originated Loans and Leases [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	3,899	949
Substandard [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	73,872	112,601
Substandard [Member] | Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	66,129	99,747
Substandard [Member] | Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	7,743	12,854
Doubtful [Member] | Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,650	1,195
Doubtful [Member] | Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	321	399
Doubtful [Member] | Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	$ 2,329	$ 796