Residential Mortgage Servicing Rights (Sensitivity Analysis of Current Fair Value to Changes in Discount and Prepayment Speed Assumptions) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Transfers and Servicing [Abstract]
Effect on fair value of a 10% adverse change	$ (6,101)	$ (6,075)
Effect on fair value of a 20% adverse change	(11,711)	(11,720)
Effect on fair value of a 100 basis point adverse change	(5,116)	(5,817)
Effect on fair value of a 200 basis point adverse change	$ (9,868)	$ (11,118)

Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of One Percent Adverse Change in Discount Rate

No definition available.

+ Details

Name:	umpq_SensitivityAnalysisOfFairValueTransferorsInterestsInTransferredFinancialAssetsImpactOfOnePercentAdverseChangeInDiscountRate
Namespace Prefix:	umpq_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of Two Percent Adverse Change in Discount Rate

+ References

No definition available.

+ Details

Name:	umpq_SensitivityAnalysisOfFairValueTransferorsInterestsInTransferredFinancialAssetsImpactOfTwoPercentAdverseChangeInDiscountRate
Namespace Prefix:	umpq_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The hypothetical financial impact of a 10 percent adverse change of prepayment speed on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82924980&loc=d3e107314-111719

+ Details

Name:	us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf10PercentAdverseChangeInPrepaymentSpeed
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The hypothetical financial impact of a 20 percent adverse change of prepayment speed on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

+ Details

Name:	us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf20PercentAdverseChangeInPrepaymentSpeed
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_TransfersAndServicingAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration