Regulatory Capital (Summary Of Company's Capital Amounts And Ratios) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Total Capital, Actual Amount	$ 1,287,560	$ 1,253,333
Total Capital, Actual Ratio	17.16%	17.62%
Total Capital, For Capital Adequacy purposes Amount	600,261	569,050
Total Capital, For Capital Adequacy purposes Ratio	8.00%	8.00%
Total Capital, To be Well Capitalized Amount	750,326	711,313
Total Capital, To be Well Capitalized Ratio	10.00%	10.00%
Tier I Capital , Actual Amount	1,193,740	1,164,226
Tier I Capital , Actual Ratio	15.91%	16.36%
Tier I Capital , For Capital Adequacy purposes Amount	300,123	284,652
Tier I Capital , For Capital Adequacy purposes Ratio	4.00%	4.00%
Tier I Capital , To be Well Capitalized Amount	450,185	426,978
Tier I Capital , To be Well Capitalized Ratio	6.00%	6.00%
Tier I Capital (to Average Assets) , Actual Amount	1,193,740	1,164,226
Tier I Capital (to Average Assets), Actual Ratio	10.91%	10.56%
Tier I Capital (to Average Assets), For Capital Adequacy purposes Amount	437,668	440,995
Tier I Capital (to Average Assets), For Capital Adequacy purposes Ratio	4.00%	4.00%
Tier I Capital (to Average Assets), To be Well Capitalized Amount	547,085	551,243
Tier I Capital (to Average Assets), To be Well Capitalized Ratio	5.00%	5.00%
Umpqua Bank [Member]
Total Capital, Actual Amount	1,163,611	1,085,839
Total Capital, Actual Ratio	15.53%	15.27%
Total Capital, For Capital Adequacy purposes Amount	599,413	568,874
Total Capital, For Capital Adequacy purposes Ratio	8.00%	8.00%
Total Capital, To be Well Capitalized Amount	749,267	711,093
Total Capital, To be Well Capitalized Ratio	10.00%	10.00%
Tier I Capital , Actual Amount	1,069,914	996,798
Tier I Capital , Actual Ratio	14.28%	14.02%
Tier I Capital , For Capital Adequacy purposes Amount	299,696	284,393
Tier I Capital , For Capital Adequacy purposes Ratio	4.00%	4.00%
Tier I Capital , To be Well Capitalized Amount	449,544	426,590
Tier I Capital , To be Well Capitalized Ratio	6.00%	6.00%
Tier I Capital (to Average Assets) , Actual Amount	1,069,914	996,798
Tier I Capital (to Average Assets), Actual Ratio	9.78%	9.04%
Tier I Capital (to Average Assets), For Capital Adequacy purposes Amount	437,593	441,061
Tier I Capital (to Average Assets), For Capital Adequacy purposes Ratio	4.00%	4.00%
Tier I Capital (to Average Assets), To be Well Capitalized Amount	$ 546,991	$ 551,326
Tier I Capital (to Average Assets), To be Well Capitalized Ratio	5.00%	5.00%