Note 1 - Basis of Presentation and Summary of Significant Accounting Policies (Details Textual) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)
Number of Operating Segments	2
Assets, Total	$ 3,281,016		$ 3,302,924	$ 3,285,480
Allowance for Loan and Lease Losses, Period Increase (Decrease), Total	2,000
Operating Lease, Right-of-Use Asset	16,392	$ 17,000
Operating Lease, Liability, Total	17,713	$ 18,000
WM&T [Member]
Assets, Total	$ 3,000,000

Amount of increase (decrease) of allowance reserve for credit loss.

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of lessee's right to use underlying asset under operating lease.

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