Parent Company Financial Statements (Schedule Of Condensed Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Other assets	$ 224,018	$ 227,637
Total assets	25,741,439	24,813,119	$ 23,406,381
Other liabilities	266,430	306,854
Junior subordinated debentures, at fair value	277,155	262,209
Junior subordinated debentures, at amortized cost	100,609	100,931
Total liabilities	21,726,653	20,896,324
Shareholders' equity	4,014,786	3,916,795
Total liabilities and shareholders' equity	25,741,439	24,813,119
Umpqua Bank
Condensed Financial Statements, Captions [Line Items]
Non-interest bearing deposits with subsidiary bank	124,915	92,540
Investments in Bank subsidiary	4,299,940	4,204,591
Investments in Nonbank subsidiaries	33,368	43,488
Other assets	382	3,914
Total assets	4,458,605	4,344,533
Payable to bank subsidiary	115	75
Other liabilities	65,940	64,523
Junior subordinated debentures, at fair value	277,155	262,209
Junior subordinated debentures, at amortized cost	100,609	100,931
Total liabilities	443,819	427,738
Shareholders' equity	4,014,786	3,916,795
Total liabilities and shareholders' equity	$ 4,458,605	$ 4,344,533