Business Combinations (Narrative) (Details) (USD $)	6 Months Ended		0 Months Ended						0 Months Ended		6 Months Ended					0 Months Ended		3 Months Ended		6 Months Ended					6 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2011 Sto	Jun. 30, 2010	Jan. 22, 2010 Evergreen Bank [Member]	Jun. 30, 2011 Evergreen Bank [Member]	Jun. 30, 2011 Evergreen Bank [Member] FDIC Loss and Loss Recovery Sharing And Absorption Threshold Minimum [Member]	Jun. 30, 2011 Evergreen Bank [Member] FDIC Loss and Loss Recovery Sharing And Absorption Threshold Maximum [Member]	Jun. 30, 2011 Evergreen Bank [Member] Non-Single Family Residential [Member]	Jun. 30, 2011 Evergreen Bank [Member] Single Family Residential [Member]	Feb. 26, 2010 Rainier Pacific Bank [Member]	Jun. 30, 2011 Rainier Pacific Bank [Member]	Jun. 30, 2011 Rainier Pacific Bank [Member]	Jun. 30, 2011 Rainier Pacific Bank [Member] FDIC Loss and Loss Recovery Sharing And Absorption Threshold Minimum [Member]	Jun. 30, 2011 Rainier Pacific Bank [Member] FDIC Loss and Loss Recovery Sharing And Absorption Threshold Maximum [Member]	Jun. 30, 2011 Rainier Pacific Bank [Member] Non-Single Family Residential [Member]	Jun. 30, 2011 Rainier Pacific Bank [Member] Single Family Residential [Member]	Jun. 18, 2010 Nevada Security Bank [Member]	Jun. 30, 2011 Nevada Security Bank [Member]	Jun. 30, 2011 Nevada Security Bank [Member]	Jun. 30, 2010 Nevada Security Bank [Member]	Jun. 30, 2011 Nevada Security Bank [Member]	Jun. 30, 2010 Nevada Security Bank [Member]	Jun. 30, 2011 Nevada Security Bank [Member] FDIC Loss and Loss Recovery Sharing And Absorption [Member]	Jun. 30, 2011 Nevada Security Bank [Member] Non-Single Family Residential [Member]	Jun. 30, 2011 Nevada Security Bank [Member] Single Family Residential [Member]	Jun. 30, 2011 Evergreen And Ranier [Member]	Jun. 30, 2011 Evergreen And Ranier [Member]	Jun. 30, 2010 Evergreen And Ranier [Member]	Jun. 30, 2011 Evergreen And Ranier [Member]	Jun. 30, 2010 Evergreen And Ranier [Member]
Date that Umpqua Bank assumed operations											February 26, 2010									June 18, 2010					January 22, 2010
FDIC loss absorption percentage					80.00%	95.00%						80.00%	95.00%									80.00%
FDIC loss recoveries absorption percentage					80.00%	95.00%						80.00%	95.00%									80.00%
Covered asset value for FDIC absorption					$ 90,000,000	$ 90,000,000						$ 95,000,000	$ 95,000,000
Umpqua to incur losses before loss sharing, amount	30,200,000
Length of loss sharing arrangement, by loan type, years							5	10						5	10								5	10
Length of loss recovery provisions, by loan type, years							8	10						8	10								8	10
Number of store locations assumed				6							14							5		5
Business acquisition revenue	9,400,000.0000																	2,800,000	529,000	9,800,000							10,400,000	24,500,000	22,800,000
Non-interest expense from acquisition, included in Umpqua operations																		2,600,000	582,000	6,100,000						4,800,000	6,600,000	9,400,000	11,300,000
Earnings (loss) added by acquisition, included in Umpqua operations																		532,000,000	34,000	627,000,000						1,400,000	2,500,000	5,400,000	7,600,000
Merger-related expenses, incurred in connection with acquisitions																		12,000	1,600,000	23,000	3,300,000					52,000,000		102,000,000
Cost basis net assets (liabilities)				58,800,000							50,300,000							53,600,000		53,600,000
Core deposit intangible assets recognized and deductable for income tax purposes										1,100,000							322,000
Purchase of furniture equipment and real estate				344,000							26,300,000							2.0		2.0
Cash payment received from (paid to) the FDIC											59,400,000							30,000,000		30,000,000
Bargain purchase gain on acquisition		6,437,000	6,437,000
(Goodwill) recognized in connection with acquisition											$ 27,500,000							$ 36,500,000		$ 36,500,000
Number of store locations available for purchase under option agreement	1