Subsequent Events (Details) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 22, 2013 First Lansing Bancorp, Inc. [Member] Subsequent Event [Member]	Jan. 22, 2013 First Lansing Bancorp, Inc. [Member] Chicago, Illinois [Member] Subsequent Event [Member] locations	Jan. 22, 2013 First Lansing Bancorp, Inc. [Member] Northwest Indiana [Member] Subsequent Event [Member] locations	Feb. 01, 2013 Second Federal [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Number of Locations					7	1
Assets to be acquired	$ 1,158,925,000	$ 1,257,085,000	$ 673,277,000	$ 370,000,000
Deposits to be assumed				325,000,000
Deposits disposed of							$ 149,000,000