Acquisitions (Activity for Acquired Loans) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period		$ 298,257	$ 137,961
Accretable Yield Additions, Net of Reductions	[1]	(6,681)	(696)
Accretion recognized in interest income		(16,962)	(8,205)
Balance at end of period		274,614	129,060
Northwestern Bancorp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period		82,623	104,675
Accretable Yield Additions, Net of Reductions	[1]	(2,254)	(1,410)
Accretion recognized in interest income		(4,001)	(4,998)
Balance at end of period		76,368	98,267
OAK [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period		28,077	33,286
Accretable Yield Additions, Net of Reductions	[1]	1,516	714
Accretion recognized in interest income		(2,557)	(3,207)
Balance at end of period		27,036	$ 30,793
Lake Michigan Financial Corp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period		152,999
Accretable Yield Additions, Net of Reductions	[1]	(6,071)
Accretion recognized in interest income		(8,953)
Balance at end of period		137,975
Monarch Community Bancorp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period		34,558
Accretable Yield Additions, Net of Reductions	[1]	128
Accretion recognized in interest income		(1,451)
Balance at end of period		$ 33,235

[1] Represents additions of estimated contractual interest expected to be collected from acquired loans being renewed or extended, less reductions in contractual interest resulting from the early payoff of acquired loans.