Subsequent Events (Narrative) (Details) (USD $)	6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Jun. 30, 2011 Northbrook [Member]	Mar. 31, 2011 Elgin State Bancorp, Inc [Member]
Assets under management	$ 2,400,000,000
Total assets	14,615,897,000	13,980,156,000	13,708,560,000	959,000,000	277,000,000
Total deposits				$ 887,000,000	$ 249,000,000
Acquired assets	12.00%
Non-broker deposits	0.50%