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Note 2 - Business Combination (Details) |  | 12 Months Ended
--- | --- | ---
Jun. 01, 2014 USD ($) shares | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($)
Note 2 - Business Combination (Details) [Line Items] |  |  |  |
Goodwill |  | $ 49,473,000 | $ 49,473,000 |
Business Combination, Acquisition Related Costs |  | 0 | 5,447,000 | $ 1,246,000
Firstbank Corporation [Member] |  |  |  |
Note 2 - Business Combination (Details) [Line Items] |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets | $ 1,452,880,000 | $ 1,500,000,000 |  |
Business Combination, Branches Acquired | 46 | 46 |  |
Business Acquisition, Conversion of Stock Per Share (in Shares) | shares | 1 |  |  |
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in Shares) | shares | 8,087,272 |  |  |
Goodwill | $ 49,473,000 |  |  |
Business Combination, Acquisition Related Costs |  |  | $ 5,400,000 | $ 1,200,000
Business Combination, Acquired Receivables and Certain Loans, Estimated Uncollectible Cash Flows | 10,400,000 |  |  |
Business Combination Acquired Receivables And Certain Loans Preacquisition Charge-offs | 2,800,000 |  |  |
Business Combination Acquired Receivables And Certain Loans Estimated UncollectibleI nterest | 3,900,000 |  |  |
Business Combination, Acquired Receivables, Gross Contractual Amount | 926,400,000 |  |  |
Business Combination, Acquired Receivables, Unaccredted Discount | $ 8,100,000 |  |  |

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- Definition The number of shares that each share of the acquiree is converted into shares of the acquirer. + References No definition available. + Details
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- Definition For receivables acquired in a business combination, including certain loans and debt securities acquired in a transfer (as defined), this element represents the best estimate at the acquisition date of the contractual cash flows not expected to be collected, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables. + References No definition available. + Details
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- Definition For receivables acquired in a business combination, including certain loans and debt securities acquired in a transfer (as defined), this element represents the best estimate at the acquisition date of the future interest not expected to be collected, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables. + References No definition available. + Details
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- Definition Amount of expense to write-down the amortized cost basis of loans, before acquisition, to fair value. Expressed as a component of nonaccretable difference. + References No definition available. + Details
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- Definition For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the unaccreted discount. + References No definition available. + Details
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- Definition The number of banking branches acquired in a business combination. + References No definition available. + Details
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- Definition Number of shares of equity interests issued or issuable to acquire entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(4) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 + Details
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- Definition For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the gross contractual amounts receivable, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
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- Definition This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e1043-128460 + Details
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- Definition Amount of assets acquired at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
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- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266 + Details
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