Preferred Stock Converted Into Common Stock, Shares

No definition available.

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Balance Type:	na
Period Type:	instant

- Definition

Special Dividends Payable, Amount Per Share

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Warrant Activity, Net Shares

+ References

No definition available.

+ Details

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- Details

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Balance Type:	na
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(i)(2))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph i

-Subparagraph 2

-Article 4

+ Details

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

+ Details

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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of new stock issued during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

+ Details

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

+ Details

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Details

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- Details

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Shareholders' Equity (Details) (USD $)	0 Months Ended				12 Months Ended	0 Months Ended		12 Months Ended
Shareholders' Equity (Details) (USD $)	Oct. 23, 2014	Jul. 23, 2014	Apr. 23, 2014	Jan. 23, 2014	Dec. 31, 2014	Jan. 29, 2015	Apr. 02, 2013	Dec. 31, 2013
Class of Stock [Line Items]
Preferred Stock Converted Into Common Stock, Shares					102,363
Class of Warrant or Right, Exercise Price of Warrants or Rights							8.58
Class of Warrant or Right, Number of Securities Called by Warrants or Rights					0
Warrant Activity, Net Shares					1,722,497colb_WarrantActivityNetShares
Declared quarterly cash dividend	$ 0.16	$ 0.14	$ 0.12	$ 0.12
Special Dividends Payable, Amount Per Share	$ 0.14	$ 0.14	$ 0.12
Stock Repurchase Program, Number of Shares Authorized to be Repurchased					2,000,000
Stock Repurchased During Period, Shares					0
Dividend Declared [Member]
Class of Stock [Line Items]
Declared quarterly cash dividend						$ 0.16
Special Dividends Payable, Amount Per Share						$ 0.14
Preferred Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues					0		8,782	9,000