Organization and Nature of Business and Summary of Significant Accounting Policies (Branches) (Details)	Dec. 31, 2015 Bank_branches
Des Moines, Iowa metropolitan area [Member]
Number of bank branches by location [Line Items]
Number of bank branches	8
Iowa City, Iowa [Member]
Number of bank branches by location [Line Items]
Number of bank branches	1
Coralville, Iowa [Member]
Number of bank branches by location [Line Items]
Number of bank branches	1
Rochester, Minnesota [Member]
Number of bank branches by location [Line Items]
Number of bank branches	1