Other Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Capital commitments relating to investments	$ 5.3	$ 1.4

Capital commitments to limited partnerships that operate qualified affordable housing projects.

No definition available.

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