Business Combinations (Detail) $ in Thousands				3 Months Ended									12 Months Ended
	Jan. 04, 2016 USD ($)	Dec. 01, 2015 USD ($) Branch shares	Nov. 01, 2014 USD ($) Branch shares	Dec. 31, 2016 USD ($) Branch shares	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) shares	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2016 USD ($) Branch shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($)	Sep. 30, 2014 shares
Business Acquisition [Line Items]
Shares of common stock authorized (in shares) | shares				332,023,233				332,023,233					332,023,233	332,023,233
Charge within income tax expense				$ 18,336	$ 17,049	$ 15,460	$ 14,389	$ (10,987)	$ 10,179	$ 12,474	$ 12,272		$ 65,234	$ 23,938	$ 31,062
Florida
Business Acquisition [Line Items]
Number of branches operated | Branch				31									31
Number of branches closed | Branch													5
Masters Coverage Corp.
Business Acquisition [Line Items]
Total consideration for acquisition	$ 1,400
CNL Bancshares, Inc.
Business Acquisition [Line Items]
Total consideration for acquisition		$ 230,000
Assets acquired		1,600,000
Loans acquired		825,000
Deposits acquired		$ 1,200,000
Conversion ratio for shares issued		0.705
Shares issued in acquisition | shares		20,600,000
Merger expenses													$ 1,800
Charge within income tax expense													$ 3,300
CNL Bancshares, Inc. | Florida
Business Acquisition [Line Items]
Number of branches acquired | Branch		16
First United Bancorp, Inc.
Business Acquisition [Line Items]
Total consideration for acquisition			$ 300,000
Assets acquired			$ 1,700,000
Conversion ratio for shares issued			0.89
Shares issued in acquisition | shares			30,700,000
Merger expenses														$ 2,600
Loans			$ 1,200,000
Total deposits			1,400,000
Cash portion of consideration			$ 8,900
Shares of common stock authorized (in shares) | shares																100,000,000
Charge within income tax expense												$ 7,600
First United Bancorp, Inc. | Florida
Business Acquisition [Line Items]
Number of branches acquired | Branch			20