Summary of Significant Accounting Policies - Additional Information (Detail)		12 Months Ended
	Feb. 24, 2016 shares	Dec. 31, 2015 USD ($) Entity Portfolio Security shares	Dec. 31, 2014 Security shares
Summary Of Significant Accounting Policies [Line Items]
Number of variable interest entity included in consolidated statements \| Entity		1
Instruments with an original maturity		Less than 90 days
Number of Investment portfolios \| Portfolio		3
Number of securities held as trading securities \| Security		0	0
Minimum percentage chances of tax benefit to be realized on examination		50.00%
Tax benefit \| $		$ 0
Stock Options Granted, Number of Shares		96,150	83,400
Non Qualified Stock Options [Member] \| Subsequent Event [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock Options Granted, Number of Shares	97,000
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful lives for all premises and equipment		40 years
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful lives for all premises and equipment		3 years