Nature of Operations and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012 Minimum	Dec. 31, 2012 Maximum	Jan. 01, 2013 Subsequent event	Dec. 31, 2012 Federal Reserve Bank of Chicago and Federal Home Loan Bank of Indianapolis
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Cash accounts exceeding federally insured limits	$ 11,510,000
Uninsured accounts					2,328,000
Money market account for investment purchases	8,300,000
Noninterest-bearing transaction accounts FDIC insurance limit				$ 250,000
Premises and equipment estimated useful lives		3 years	50 years
Intangible assets amortization period		5 years	11 years