Parent Company Financial Statements (Schedule Of Condensed Statements Of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net income	$ 63,019	$ 57,607	$ 54,784	$ 47,129	$ 52,582	$ 58,883	$ 17,542	$ 18,651	$ 222,539	$ 147,658	$ 98,291
Depreciation, amortization and accretion									51,593	39,209	23,636
Change in fair value of junior subordinated debentures									6,163	5,849	2,193
Net decrease (increase) in other assets									25,248	(45,913)	31,902
Net decrease in other liabilities									15,290	38,632	(7,589)
Net cash provided by operating activities									376,740	359,196	417,932
Acquisitions									0	116,867	(149,658)
Net cash used by investing activities									(1,756,911)	242,140	276,237
Dividends paid on common stock									(134,618)	(99,233)	(50,768)
Stock repurchased									(14,589)	(7,183)	(9,360)
Proceeds from exercise of stock options									925	6,116	6,398
Net cash provided (used) by financing activities									548,725	213,412	(447,533)
Net (decrease) increase in cash and cash equivalents									(831,446)	814,748	246,636
Cash and cash equivalents, beginning of year				1,605,171				790,423	1,605,171	790,423	543,787
Cash and cash equivalents, end of year	773,725				1,605,171				773,725	1,605,171	790,423
Umpqua Bank [Member]
Condensed Financial Statements, Captions [Line Items]
Net income									222,539	147,658	98,291
Equity in undistributed earnings of subsidiaries									(84,116)	91,831	(43,311)
Depreciation, amortization and accretion									(322)	(322)	(322)
Change in fair value of junior subordinated debentures									6,163	5,849	2,193
Net decrease (increase) in other assets									617	(6,020)	(92)
Net decrease in other liabilities									(2,903)	(8,708)	(1,361)
Net cash provided by operating activities									141,978	230,288	55,398
Investment in subsidiaries									(5,000)	6	(2,928)
Acquisitions									0	(102,143)	0
Net cash used by investing activities									(5,000)	(102,137)	(2,928)
Net decrease in payables to subsidiaries									0	(4)	(8,448)
Dividends paid on common stock									(134,618)	(99,233)	(50,767)
Stock repurchased									(14,589)	(7,183)	(9,356)
Proceeds from exercise of stock options									1,481	7,692	6,397
Net cash provided (used) by financing activities									(147,726)	(98,728)	(62,174)
Net (decrease) increase in cash and cash equivalents									(10,748)	29,423	(9,704)
Cash and cash equivalents, beginning of year				$ 102,102				$ 72,679	102,102	72,679	82,383
Cash and cash equivalents, end of year	$ 91,354				$ 102,102				$ 91,354	$ 102,102	$ 72,679