Loans and Allowance for Loan Losses - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 10,333,873		$ 10,333,873		$ 9,506,094
Outstanding contractual balance receivable of acquired loans	1,601,476		1,601,476		1,449,227
Commercial construction loans	274,489		274,489		252,842
Payoffs received on loans in excess of expected cash flows			242		440
Threshold period past due for default status of trade accounts receivable	90 days	90 days	90 days	90 days
Minimum corporation reserves for commercial loan	500		500
Minimum amount to allocate specific valuation allowance	500		500
Recorded Investment	5,228		5,228
Allowance for loan losses			5,560		5,900
Restructured loans returned to performing status			2,915
Valuation for impairment of loans with pooled reserves	500		500		500
Pooled reserves for all other classes of loans			1,062		1,005
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	3,577,933		3,577,933		3,245,209
Recorded Investment	40,788		40,788		44,075
Allowance for loan losses			2,911		3,093
Commercial Real Estate [Member] | FLORIDA [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial real estate loans	32,935		32,935		39,379
Percentage of loan portfolio	0.30%		0.30%		0.40%
Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,037,519		1,037,519		965,771
Percentage of loan portfolio	1.70%		1.70%		1.90%
Consumer loans	175,802		175,802		179,970
Recorded Investment	1,604		1,604		597
Commercial Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of loan portfolio	2.70%		2.70%		2.70%
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,103,896		2,103,896		1,881,474
Recorded Investment	9,837		9,837		7,423
Allowance for loan losses			674		786
Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,512,149		1,512,149		1,467,236
Recorded Investment	12,520		12,520		10,577
Allowance for loan losses			1,405		727
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,145,286		1,145,286		1,086,739
Recorded Investment	14,122		14,122		14,012
Allowance for loan losses			207		970
Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	729,513		729,513		655,587
Recorded Investment	1,368		1,368		1,202
Allowance for loan losses			248		324
Consumer Lines Of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses			115
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,498,234		1,498,234		1,345,429
Purchased Credit-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying Amount	12,953		12,953		21,192
Outstanding contractual receivable of PCI loan	35,352		35,352		56,500
Recorded Investment	13,401		13,401		22,192
Owner-Occupied [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of loan portfolio	41.10%		41.10%		43.10%
Non-Owner-Occupied [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of loan portfolio	58.90%		58.90%		56.90%
Specific reserves for commercial TDRs [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reserves in allowance for loan losses, TDRs	446		446		561
Pooled reserves for commercial TDRs [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reserves in allowance for loan losses, TDRs	$ 212		$ 212		$ 193
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due for default non-accrual status of trade accounts receivable			90 days
Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due for default non-accrual status of trade accounts receivable			120 days
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due for default non-accrual status of trade accounts receivable			180 days