Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Income Taxes [Line Items]
Income tax expense (benefit)	$ 9,000	$ 632,000
Effective tax rate	1.10%	40.50%
Net deferred tax asset	0		0
Valuation allowance	17,000,000		17,300,000
Unrecognized tax benefits	2,600,000		2,200,000
Tax benefit that, if recogniced, would impact effective tax rate	0
Accrued interest or penalties	$ 0		$ 0
Minimum
Income Taxes [Line Items]
Income tax year under examination by the IRS	2010
Minimum | Gateway Bancorp Inc.
Income Taxes [Line Items]
Income tax year under examination by the IRS	2008
Maximum
Income Taxes [Line Items]
Income tax year under examination by the IRS	2011
Maximum | Gateway Bancorp Inc.
Income Taxes [Line Items]
Income tax year under examination by the IRS	2009