Junior Subordinated Debentures Issued to Capital Trusts - Schedule of Outstanding Junior Subordinated Debentures and Related Trust Preferred Securities Issued by Each Trust (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Carrying value	$ 188,522		$ 185,598
GCB Capital Trust III [Member]
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Annual interest rate, base rate	3-month LIBOR
Annual interest rate spread, percentage	1.40%
Trust Preferred Securities Subject to Mandatory Redemption [Member] | State Bancorp Capital Trust I [Member]
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Face value	10,000
Issuance date	October 29, 2002
Distribution dates	Quarterly	[1]
Annual interest rate, base rate	3-month LIBOR	[2]
Annual interest rate spread, percentage	3.45%	[2]
Trust Preferred Securities Subject to Mandatory Redemption [Member] | State Bancorp Capital Trust II [Member]
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Face value	10,000
Issuance date	December 19, 2003
Distribution dates	Quarterly	[1]
Annual interest rate, base rate	3-month LIBOR	[2]
Annual interest rate spread, percentage	2.85%	[2]
Trust Preferred Securities Subject to Mandatory Redemption [Member] | VNB Capital Trust I [Member]
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Annual interest rate	7.75%	[2]
Face value	142,313		152,300
Issuance date	November 7, 2001
Distribution dates	Quarterly	[1]
Trust Preferred Securities Subject to Mandatory Redemption [Member] | GCB Capital Trust III [Member]
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Annual interest rate	6.96%	[2]
Face value	24,000		24,000
Issuance date	July 2, 2007
Distribution dates	Quarterly	[1]
Subordinated Debentures Subject to Mandatory Redemption [Member] | State Bancorp Capital Trust I [Member]
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Carrying value	8,324	[3]
Contractual principal balance	10,310
Stated maturity date	Nov. 07, 2032
Initial call date	Nov. 07, 2007
Annual interest rate, base rate	3-month LIBOR	[2]
Annual interest rate spread, percentage	3.45%	[2]
Subordinated Debentures Subject to Mandatory Redemption [Member] | State Bancorp Capital Trust II [Member]
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Carrying value	7,552	[3]
Contractual principal balance	10,310
Stated maturity date	Jan. 23, 2034
Initial call date	Jan. 23, 2009
Annual interest rate, base rate	3-month LIBOR	[2]
Annual interest rate spread, percentage	2.85%	[2]
Subordinated Debentures Subject to Mandatory Redemption [Member] | VNB Capital Trust I [Member]
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Carrying value	147,595	[3]	160,500
Contractual principal balance	146,715		157,000
Annual interest rate	7.75%	[2]
Stated maturity date	Dec. 15, 2031
Initial call date	Nov. 07, 2006
Subordinated Debentures Subject to Mandatory Redemption [Member] | GCB Capital Trust III [Member]
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Carrying value	25,051	[3]	25,100
Contractual principal balance	$ 24,743		$ 24,700
Annual interest rate	6.96%	[2]
Stated maturity date	Jul. 30, 2037
Initial call date	Jul. 30, 2017

[1] All cash distributions are cumulative.

[2] Interest on GCB Capital Trust III is fixed until July 30, 2017, then resets to 3-month LIBOR plus 1.4 percent. The annual interest rate for GCB Capital Trust III, State Bancorp Capital Trust I, and State Bancorp Capital Trust II excludes the effect of the purchase accounting adjustments.

[3] The carrying value for GCB Capital Trust II includes an unamortized purchase accounting premium of $308 thousand, and the carrying values for State Bancorp Capital Trust I and State Bancorp Capital Trust II include purchase accounting discounts of $2.0 million and $2.8 million, respectively.