Borrowings Textuals (Details) - USD ($)		1 Months Ended
	Aug. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	May 31, 2015
Debt Disclosure [Abstract]
FHLB advances		$ 5,100,000,000
Debt Instrument [Line Items]
Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25 % due in 2032 (5)				$ 18,600,000
Line of Credit [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 145,000,000.0
Long-term borrowings, Amount	125,000,000	124,698,000	$ 25,000,000
Repayment of debt	25,000,000
Line of Credit [Member] | Term Line of Credit [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	125,000,000.0
Line of Credit [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	20,000,000.0
Line of Credit Acquired in Merger With Talmer [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Repayment of debt	37,500,000
Talmer Bank [Member]
Debt Instrument [Line Items]
Debt assumed in acquisition	$ 687,100,000
Repayment of assumed debt		$ 142,200,000