Business Combinations (Pro Forma Results of Operations) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended														6 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2013 Pro Forma [Member]	Dec. 31, 2012 Pro Forma [Member]	Dec. 31, 2013 Acquisition-related Costs [Member]		Dec. 31, 2012 Acquisition-related Costs [Member]		Dec. 31, 2013 UmpquaFinPacAcquisition [Member]	Dec. 31, 2012 UmpquaFinPacAcquisition [Member]	Dec. 31, 2013 Financial Pacific Holding Corp [Member]	Dec. 31, 2013 Financial Pacific Holding Corp [Member]		Dec. 31, 2012 Financial Pacific Holding Corp [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net interest income	$ 110,074	$ 106,809	$ 93,893	$ 94,189	$ 101,829	$ 102,040	$ 101,012	$ 102,355	$ 404,965		$ 407,236		$ 428,452		$ 423,600	$ 452,713	$ (6,891)	[1]	$ (5,332)	[1]	$ 404,965	$ 407,236		$ 25,526	[2]	$ 50,809	[3]
Provision for non-covered loan and lease losses	3,840	3,008	2,993	6,988	4,913	7,078	6,638	3,167	16,829		21,796		46,220		20,101	29,087	0	[4]	0	[4]	16,829	21,796		3,272	[2]	7,291	[3]
(RECAPTURE OF) PROVISION FOR COVERED LOAN LOSSES	(1,369)	(1,904)	(3,072)	232	3,103	2,927	1,406	(31)	(6,113)		7,405		16,141		(6,113)	7,405	0		0		(6,113)	7,405		0	[2]	0	[3]
Non-interest income	26,785	26,144	34,497	34,015	46,987	33,679	28,926	27,237	121,441		136,829		84,118		122,753	140,961	0		0		121,441	136,829		1,312	[2]	4,132	[3]
Non-interest expense	95,364	95,604	87,931	85,762	98,046	86,974	86,936	87,696	364,661		359,652		338,971		373,181	374,517	(76)	[5]	(1,236)	[6]	364,661	359,652	8,800	8,596	[2]	16,101
Income before income taxes	39,024	36,245	40,538	35,222	42,754	38,740	34,958	38,760	151,029		155,212		111,238		159,184	182,665	(6,815)		(4,096)		151,029	155,212		14,970	[2]	31,549
Provision for income taxes	13,754	12,768	14,285	11,861	14,796	13,587	11,681	13,257	52,668		53,321		36,742		55,668	64,079	(2,835)	[7]	(1,434)	[7]	52,668	53,321		5,835	[2]	12,192	[3]
Net income	25,270	23,477	26,253	23,361	27,958	25,153	23,277	25,503	98,361		101,891		74,496		103,516	118,586	(3,980)		(2,662)		98,361	101,891	9,500	9,135	[2]	19,357	[3]
Dividends and undistributed earnings allocated to participating securities	212	196	197	183	183	170	162	167	788	[8]	682	[8]	356	[8]	829	794	41		112		788	682		0	[2]	0	[3]
Net earnings available to common shareholders	25,058	23,281	26,056	23,178	27,775	24,983	23,115	25,336	97,573		101,209		74,140		102,687	117,792	(4,021)		(2,774)		97,573	101,209		9,135	[2]	19,357	[3]
Earnings per share:
Basic earnings per common share	$ 0.22	$ 0.21	$ 0.23	$ 0.21	$ 0.25	$ 0.22	$ 0.21	$ 0.23	$ 0.87		$ 0.90		$ 0.65		$ 0.92	$ 1.05					$ 0.87	$ 0.90
Diluted earnings per common share	$ 0.22	$ 0.21	$ 0.23	$ 0.21	$ 0.25	$ 0.22	$ 0.21	$ 0.23	$ 0.87		$ 0.90		$ 0.65		$ 0.92	$ 1.05					$ 0.87	$ 0.90
Average shares outstanding:
Basic (in shares)									111,938		111,935		114,220		111,938	111,935					111,938	111,935
Diluted (in shares)									112,176		112,151		114,409		112,176	112,151					112,176	112,151
Merger related expenses									$ 8,836		$ 2,338		$ 360											$ 1,600
Statutory Federal income tax rate									35.00%		35.00%		35.00%				35.00%		35.00%

[1] Adjustment of interest income from leases due to the estimated loss of income from the write-off of FinPac's loan mark (related to a prior acquisition) and the amortization of the new interest rate mark and the accretion of the acquisition accounting adjustment relating to the credit mark. The amortization period will be the contractual lives of the leases, which is approximately four years, and will be amortized into income using the effective yield method.

[2] FinPac amounts represent results from January 1, 2013 to June 30, 2013.

[3] FinPac amounts represent results from January 1, 2012 to December 31, 2012.

[4] As acquired leases are recorded at fair value, Umpqua would expect a reduction in the historical provision for loan and leases losses from FinPac; however, no adjustment to the historical amount of FinPac provision for loan and lease losses is reflected.

[5] Adjustment to reflect additional compensation expense related to restricted stock granted to FinPac management and the removal of FinPac director compensation and travel fees, and FinPac management fees of the Financial Pacific Holdings, LLC entity which was not acquired.

[6] Adjustment to reflect additional compensation expense related to restricted stock granted to FinPac management and the removal of FinPac director compensation and travel fees, FinPac management fees, and other expenses of Financial Pacific Holdings, LLC entity which was not acquired.

[7] Income tax effect of pro forma adjustments at the Company's statutory tax rate of 35%.

[8] Represents dividends paid and undistributed earnings allocated to nonvested restricted stock awards.