Mergers and Acquisitions (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	Aug. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Fair value of liabilities assumed:
Goodwill		$ 1,137,166	$ 287,393
Talmer Bank [Member]
Consideration paid:
Stock	$ 1,504,811
Cash	107,638
Total consideration	1,612,449
Fair value of identifiable assets acquired:
Cash and cash equivalents	433,352
Investment securities - AFS	808,894
Investment securities - HTM	1,657
Loans held-for-sale	244,916
Loans	4,882,864
Premises and equipment	38,793
Loan servicing rights	42,462
Other intangible assets	12,399
Interest receivable and other assets	397,660
Total identifiable assets acquired	6,862,997
Fair value of liabilities assumed:
Noninterest-bearing deposits	1,236,902
Interest-bearing deposits	4,057,968
Interest payable and other liabilities	99,176
Securities sold under agreements to repurchase with customers	19,704
Short-term borrowings	387,500
Long-term borrowings	299,597
Total liabilities assumed	6,100,847
Fair value of net identifiable assets acquired	762,150
Goodwill	$ 850,299