Business Combinations (Narrative) (Detail) (USD $)	6 Months Ended	0 Months Ended			54 Months Ended	0 Months Ended		12 Months Ended
	Jun. 30, 2014	May 16, 2014 Urban Partnership Bank, Stone Park branch [Member]	Oct. 18, 2013 Diamond Bancorp, Inc [Member] locations	May 01, 2013 First Lansing Bancorp, Inc. [Member]	Jun. 30, 2014 FDIC Assisted [Member] financial_institution	Apr. 28, 2014 Policy Billing Services Inc. [Member]	Oct. 02, 2013 Surety Financial Services [Member]	Sep. 30, 2013 Surety Financial Services [Member] locations	May 01, 2013 South And Southwest Suburbs of Chicago, Illinois [Member] First Lansing Bancorp, Inc. [Member] locations	May 01, 2013 Northwest Indiana [Member] First Lansing Bancorp, Inc. [Member] locations	Feb. 01, 2013 Second Federal [Member]
Business Acquisition [Line Items]
Effective date of acquisition		May 16, 2014	Oct. 18, 2013	May 01, 2013		Apr. 28, 2014	Oct. 01, 2013
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		$ 5,500,000	$ 169,100,000	$ 334,700,000
Assumed deposits		5,400,000	140,200,000	331,400,000
Additional goodwill recorded on acquisition	7,035,000	600,000	8,400,000	14,000,000		6,400,000	9,500,000
Number of locations			4					5	7	1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets			172,500,000	373,400,000
Business acquisition, loans acquired			91,700,000	123,000,000		7,400,000
Number of FDIC assisted banks acquired					9
FDIC loss sharing percentage on purchased loans, OREO, and certain other assets	80.00%
Divestiture of businesses, deposits disposed											149,000,000
Number of Affiliated Companies Acquired						2
Mortgage Loan Originations								$ 1,000,000,000