Fair Value Measurement (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value Disclosures [Abstract]
Other Company Stock Owned Fair Value Discount Percentage	5.00%
Carrying value of loans fully charged-off	$ 0umpq_CarryingValueOfLoansChargedOff
Net gain (loss) representing the change in fair value in earnings	$ 6,400,000	$ (14,500,000)	$ 14,000,000

For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 30

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration