Statement of Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014 Segment	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Business segments	1
Equity investments	20.00%
Loans past due days	90 days
Excess impaired credits	$ 100,000
Software purchases and developed are capitalized and amortized on straight-line basis	7 years
Future death benefit [Member]
Summary Of Significant Accounting Policies [Line Items]
Other liabilities	$ 3,900,000	$ 3,600,000