XML 48 R34.htm IDEA: XBRL DOCUMENT
v3.19.1

Accumulated Other Comprehensive Income (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Abstract] |
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] | The following table shows changes in accumulated other comprehensive income (loss) by component for the three month periods ended March 31, 2019 and 2018:
|  | Unrealized Gains and Losses on Available-for-Sale Securities (1) |  | Unrealized Gains and Losses on Pension Plan Liability (1) |  | Unrealized Gains and Losses on Hedging Instruments (1) |  | Total (1)
Three months ended March 31, 2019 |  | (in thousands)
Beginning balance |  | $ | (33,128 | ) |  | $ | (2,177 | ) |  | $ | — |  |  | $ | (35,305 | )
Other comprehensive income before reclassifications |  | 32,063 |  |  | — |  |  | 4,810 |  |  | 36,873 |
Amounts reclassified from accumulated other comprehensive loss (2) |  | 1,417 |  |  | 61 |  |  | — |  |  | 1,478 |
Net current-period other comprehensive income |  | 33,480 |  |  | 61 |  |  | 4,810 |  |  | 38,351 |
Ending balance |  | $ | 352 |  |  | $ | (2,116 | ) |  | $ | 4,810 |  |  | $ | 3,046 |
Three months ended March 31, 2018 |  |  |  |  |  |  |  |
Beginning balance |  | $ | (19,779 | ) |  | $ | (2,446 | ) |  | $ | — |  |  | $ | (22,225 | )
Adjustment pursuant to adoption of ASU 2016-01 |  | 157 |  |  | — |  |  | — |  |  | 157 |
Other comprehensive loss before reclassifications |  | (26,048 | ) |  | — |  |  | — |  |  | (26,048 | )
Amounts reclassified from accumulated other comprehensive loss (2) |  | (78 | ) |  | 61 |  |  | — |  |  | (17 | )
Net current-period other comprehensive income (loss) |  | (26,126 | ) |  | 61 |  |  | — |  |  | (26,065 | )
Ending balance |  | $ | (45,748 | ) |  | $ | (2,385 | ) |  | $ | — |  |  | $ | (48,133 | )
__________ (1) All amounts are net of tax. Amounts in parenthesis indicate debits. (2) See following table for details about these reclassifications.
Schedule of reclassifications from accumulated other comprehensive income [Table Text Block] | The following table shows details regarding the reclassifications from accumulated other comprehensive income (loss) for the three month periods ended March 31, 2019 and 2018:
|  | Amount Reclassified from Accumulated Other Comprehensive Income (Loss) |  |
|  | Three Months Ended March 31, |  | Affected line Item in the Consolidated
|  | 2019 |  | 2018 |  | Statement of Income
|  | (in thousands) |
Unrealized gains and losses on available for sale debt securities |  |  |  |  |  |
Investment securities (gains) losses, net |  | $ | (1,847 | ) |  | $ | 102 |  |  | Investment securities gains, net
|  | (1,847 | ) |  | 102 |  |  | Total before tax
|  | 430 |  |  | (24 | ) |  | Income tax provision
|  | $ | (1,417 | ) |  | $ | 78 |  |  | Net of tax
Amortization of pension plan liability |  |  |  |  |  |
Actuarial losses |  | $ | (80 | ) |  | $ | (80 | ) |  | Compensation and employee benefits
|  | (80 | ) |  | (80 | ) |  | Total before tax
|  | 19 |  |  | 19 |  |  | Income tax provision
|  | $ | (61 | ) |  | $ | (61 | ) |  | Net of tax

X
- Definition Accumulated Other Comprehensive Income (Loss) [Abstract] + References No definition available. + Details
Name: | colb_AccumulatedOtherComprehensiveIncomeLossAbstract
Namespace Prefix: | colb_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of information about items reclassified out of accumulated other comprehensive income (loss). + References No definition available. + Details
Name: | us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the components of accumulated other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669686-108580 + Details
Name: | us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration