Loans (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) bank	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Accounts, Notes, Loans and Financing Receivable
Failed banks acquired since 2009 | bank	6
Covered loans receivable	$ 202,211		$ 229,217
Deferred loan origination fees	20,900		18,700
Deposit liabilities reclassified as loans receivable	3,800		5,100
Loans with carrying value pledged to secure public deposits and other borrowings	$ 4,300,000		3,900,000
Carrying amounts of loans acquired			2,200,000
Threshold period for loans in default	30 days
Troubled Debt Restructurings
Accounts, Notes, Loans and Financing Receivable
Total TDRs	$ 218,600	$ 48,600
Accrual status TDR	94,300	21,800
Non-accrual status TDR	124,300	$ 26,800
Florida Bank Group, Inc.
Accounts, Notes, Loans and Financing Receivable
Acquired loans			300,000
Old Florida Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable
Acquired loans			1,100,000
Georgia Commerce
Accounts, Notes, Loans and Financing Receivable
Acquired loans			800,000
Loans Acquired Without Deteriorated Credit Quality
Accounts, Notes, Loans and Financing Receivable
Carrying amounts of loans acquired			2,100,000
Loans Acquired With Deteriorated Credit Quality
Accounts, Notes, Loans and Financing Receivable
Carrying amounts of loans acquired			57,800
Acquired Covered Loan
Accounts, Notes, Loans and Financing Receivable
Covered loans receivable	202,200		229,200
Acquired Covered Loan | Residential Mortgage and Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable
Covered loans receivable	$ 169,000		$ 191,700