Mergers and Acquisitions (Activity for Acquired Loans) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	$ 256,540	$ 348,048	$ 298,257	$ 137,961
Additions attributable to acquisitions	862,127	0	862,127	228,160
Additions (reductions)	7,224	(1,233)	(10,053)	1,532
Accretion recognized in interest income	(34,018)	(19,990)	(68,458)	(40,828)
Reclassification from nonaccretable difference			10,000
Balance at end of period	1,091,873	326,825	1,091,873	326,825
Talmer [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	0	0	0	0
Additions attributable to acquisitions	862,127	0	862,127	0
Additions (reductions)	0	0	0	0
Accretion recognized in interest income	(17,415)	0	(17,415)	0
Reclassification from nonaccretable difference			0
Balance at end of period	844,712	0	844,712	0
Lake Michigan [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	125,343	188,310	152,999	0
Additions attributable to acquisitions	0	0	0	190,246
Additions (reductions)	6,565	(747)	(3,800)	803
Accretion recognized in interest income	(7,968)	(10,704)	(25,259)	(14,190)
Reclassification from nonaccretable difference			0
Balance at end of period	123,940	176,859	123,940	176,859
Monarch [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	30,859	35,805	34,558	0
Additions attributable to acquisitions	0	0	0	37,914
Additions (reductions)	114	(351)	(749)	(1,492)
Accretion recognized in interest income	(1,322)	(2,085)	(4,158)	(3,053)
Reclassification from nonaccretable difference			0
Balance at end of period	29,651	33,369	29,651	33,369
Northwestern [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	73,746	91,758	82,623	104,675
Additions attributable to acquisitions	0	0	0	0
Additions (reductions)	526	(1,337)	(5,322)	(4,196)
Accretion recognized in interest income	(3,890)	(4,376)	(11,919)	(14,434)
Reclassification from nonaccretable difference			5,000
Balance at end of period	70,382	86,045	70,382	86,045
OAK [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	26,592	32,175	28,077	33,286
Additions attributable to acquisitions	0	0	0	0
Additions (reductions)	19	1,202	(182)	6,417
Accretion recognized in interest income	(3,423)	(2,825)	(9,707)	(9,151)
Reclassification from nonaccretable difference			5,000
Balance at end of period	$ 23,188	$ 30,552	$ 23,188	$ 30,552