Loans (Purchased Impaired Loans (Narrative)) (Details) - USD ($) $ in Millions	Feb. 05, 2016	Nov. 30, 2015	Sep. 11, 2015	Aug. 21, 2015	Jan. 16, 2015
Centennial Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 594.9
Estimated fair value of loans acquired	$ 581.5
Premier Valley Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 400.5
Estimated fair value of loans acquired		$ 389.8
First Scottsdale Bank, N.A.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans			$ 56.5
Estimated fair value of loans acquired			$ 54.7
Community Bancorporation of New Mexico, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans				$ 103.7
Estimated fair value of loans acquired				$ 99.5
Community Banc-Corp of Sheboygan, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans					$ 413.4
Estimated fair value of loans acquired					$ 395.0