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Shareholders' Equity Dividends Declared (Tables) | 9 Months Ended
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Sep. 30, 2021
Shareholders' Equity [Abstract] |
Dividends Declared [Table Text Block] | The following table summarizes year-to-date dividend activity:
Declared |  | Regular Cash Dividends Per Common Share |  |  |  | Record Date |  | Paid Date
January 28, 2021 |  | $ | 0.28 |  |  |  |  | February 10, 2021 |  | February 24, 2021
April 29, 2021 |  | $ | 0.28 |  |  |  |  | May 12, 2021 |  | May 26, 2021
July 29, 2021 |  | $ | 0.28 |  |  |  |  | August 11, 2021 |  | August 25, 2021
September 30, 2021 |  | $ | 0.30 |  |  |  |  | October 13, 2021 |  | October 27, 2021

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- Definition Shareholders' Equity [Abstract] + References No definition available. + Details
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Namespace Prefix: | colb_
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- Definition Tabular disclosure of information related to dividends declared, including paid and unpaid dividends. + References No definition available. + Details
Name: | us-gaap_DividendsDeclaredTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
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