Loans and Allowance for Loan Losses - Summary of Commercial Loans by Credit Quality (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Originated Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	$ 4,686,978	$ 4,560,991
Originated Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,677,152	2,640,428
Originated Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	1,848,332	1,761,668
Originated Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	161,494	158,895
Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	904,179	724,587
Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	787,446	604,781
Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	116,733	119,806
Acquired Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases
Pass [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	4,348,866	4,244,509
Pass [Member] | Originated Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,501,710	2,476,988
Pass [Member] | Originated Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	1,688,867	1,611,530
Pass [Member] | Originated Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	158,289	155,991
Pass [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	674,575	543,347
Pass [Member] | Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	575,859	442,604
Pass [Member] | Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	98,716	100,743
Pass [Member] | Acquired Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases
Special Mention [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	170,157	155,760
Special Mention [Member] | Originated Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	70,417	56,140
Special Mention [Member] | Originated Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	97,558	97,675
Special Mention [Member] | Originated Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,182	1,945
Special Mention [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	98,726	80,497
Special Mention [Member] | Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	94,461	74,315
Special Mention [Member] | Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	4,265	6,182
Special Mention [Member] | Acquired Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases
Substandard [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	166,503	159,880
Substandard [Member] | Originated Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	103,838	106,599
Substandard [Member] | Originated Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	61,642	52,322
Substandard [Member] | Originated Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	1,023	959
Substandard [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	125,008	97,952
Substandard [Member] | Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	111,306	85,086
Substandard [Member] | Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	13,702	12,866
Substandard [Member] | Acquired Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases
Doubtful [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	1,452	842
Doubtful [Member] | Originated Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	1,187	701
Doubtful [Member] | Originated Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	265	141
Doubtful [Member] | Originated Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases
Doubtful [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	5,870	2,791
Doubtful [Member] | Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	5,820	2,776
Doubtful [Member] | Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	50	15
Doubtful [Member] | Acquired Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases