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Junior subordinated debt | 12 Months Ended
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Dec. 31, 2018
Junior subordinated debentures [Abstract] |
Junior subordinated debentures [Text Block] | Junior Subordinated Debentures On November 1, 2017, with its acquisition of Pacific Continental, the Company assumed $14.4 million of trust preferred obligations. The Company redeemed $6.2 million of these obligations during 2017 and the remaining $8.2 million of obligations were redeemed in January of 2018.

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- Definition Junior subordinated debentures [Abstract] + References No definition available. + Details
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- Definition Junior subordinated debentures [Text Block] + References No definition available. + Details
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Namespace Prefix: | colb_
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