Business Combinations - Additional Information (Detail) (USD $) Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Business Acquisition [Line Items]
Acquisition date			Jan. 01, 2012
Fixed Rate Cumulative Series A Preferred Stock redeemed, value			$ 36,800,000
Short term loan for stock redemption			37,000,000
Number of years purchase warrant can be used			10 years
Number of common stock issued upon exercise of warrant	489	489	489
Exercise price of warrant	11.30	11.30	11.30
New York network [Member]
Business Acquisition [Line Items]
Number of branches in network			44
State Bancorp, Inc. [Member]
Business Acquisition [Line Items]
Assets			1,700,000,000
Loans			1,100,000,000
Total deposits			1,400,000,000
Number of branches acquired			16
Total estimated consideration for the acquisition			$ 208,000,000
State Bancorp, Inc. [Member] | New York network [Member]
Business Acquisition [Line Items]
Number of branches acquired			15
State Bancorp, Inc. [Member] | Other New York City locations [Member]
Business Acquisition [Line Items]
Number of branches acquired			5