Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The accounting and financial reporting policies of Umpqua Holdings Corporation conform to accounting principles generally accepted in the United States of America. The accompanying interim condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All material inter-company balances and transactions have been eliminated. The condensed consolidated financial statements have not been audited. A more detailed description of our accounting policies is included in the 2017 Annual Report filed on Form 10-K. These interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes contained in the 2017 Annual Report filed on Form 10-K. All references in this report to "Umpqua," "we," "our," "us," the "Company" or similar references mean Umpqua Holdings Corporation, and include our consolidated subsidiaries where the context so requires. References to "Bank" refer to our subsidiary Umpqua Bank, an Oregon state-chartered commercial bank, and references to "Umpqua Investments" refer to our subsidiary Umpqua Investments, Inc., a registered broker-dealer and investment adviser. The Bank also has a wholly-owned subsidiary, Financial Pacific Leasing Inc., a commercial equipment leasing company. Pivotus Ventures, Inc., a wholly-owned subsidiary of Umpqua Holdings Corporation, focuses on advancing bank innovation by developing new bank platforms that could have a significant impact on the experience and economics of banking. In preparing these condensed consolidated financial statements, the Company has evaluated events and transactions subsequent to March 31, 2018 for potential recognition or disclosure. In management's opinion, all accounting adjustments necessary to accurately reflect the financial position and results of operations on the accompanying financial statements have been made. These adjustments include normal and recurring accruals considered necessary for a fair and accurate presentation. The results for interim periods are not necessarily indicative of results for the full year or any other interim period. Certain reclassifications of prior period amounts have been made to conform to current classifications. Application of new accounting guidance As of January 1, 2018, Umpqua adopted the Financial Accounting Standard Board's ("FASB") Accounting Standard Update ("ASU") No. 2014-09, Revenue from Contracts with Customers and all subsequent amendments to the ASU (collectively "ASC 606"), which (i) creates a single framework for recognizing revenue from contracts with customers that are within its scope and (ii) revises when it is appropriate to recognize a gain or loss from the transfer of nonfinancial assets such as other real estate owned. The majority of Umpqua's revenues come from interest income and other sources, including loans, leases, securities, and derivatives, that are outside the scope of ASC 606. Umpqua's revenues that are within the scope of ASC 606 are presented within Non-Interest Income and are recognized as revenue as the Company satisfies its obligation to the customer. Revenues within the scope of ASC 606 include service charges on deposits, brokerage revenue, interchange income, and the sale of other real estate owned. Refer to Note 15 - Revenue from Contracts with Customers for further discussion of Umpqua's accounting policies for revenue sources within the scope of ASC 606. Umpqua adopted ASC 606 using the modified retrospective method applied on all contracts not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under ASC 606 while prior period amounts continue to be reported in accordance with legacy generally accepted accounting principles ("GAAP"). The adoption of ASC 606 did not result in a material change to the accounting for any of the in-scope revenue streams; as such, no cumulative effect adjustment was recorded. As of January 1, 2018, Umpqua applied FASB ASU No. 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The new guidance relates to the recognition and measurement of financial instruments. This ASU requires equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. Upon adoption, certain equity securities were reclassified from available for sale to the equity securities classification on the balance sheet. The ASU was applied prospectively. The amendment also requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements. This ASU also eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. The disclosures in the fair value footnote have been updated accordingly. The amendment also requires a reporting organization to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument specific credit risk (also referred to as "own credit") when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The Company's junior subordinated debentures are variable-rate instruments based on LIBOR, with the majority reseting quarterly. Applying the updated guidance, the FASB noted that the entire risk in excess of the risk free or benchmark rate could be considered instrument-specific credit risk. The Company has determined that all changes in fair value of the junior subordinated debentures are due to changes in value other than in the benchmark rate, and accordingly are instrument-specific credit risk. As such, the Company calculated the change in the discounted cash flows based on updated market credit spreads since the election of the fair value option for each junior subordinated debenture measured at fair value to be a net gain of $13.0 million. The gain was recorded, net of the tax effect, as a cumulative effect adjustment between retained earnings and accumulated other comprehensive income (loss), resulting in an adjustment of $9.7 million upon adoption. For the first quarter of 2018, the change in fair value is attributable to the change in the instrument specific credit risk of the junior subordinated debentures, as determined by the application of ASU 2016-01. Accordingly, the loss on fair value of junior subordinated debentures for the quarter ended March 31, 2018 of $1.7 million is recorded in other comprehensive income (loss), net of tax, as an other comprehensive loss of $1.3 million.

Summary of Significant Accounting Policies

The accounting and financial reporting policies of Umpqua Holdings Corporation conform to accounting principles generally accepted in the United States of America. The accompanying interim condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All material inter-company balances and transactions have been eliminated. The condensed consolidated financial statements have not been audited. A more detailed description of our accounting policies is included in the 2017 Annual Report filed on Form 10-K. These interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes contained in the 2017 Annual Report filed on Form 10-K. All references in this report to "Umpqua," "we," "our," "us," the "Company" or similar references mean Umpqua Holdings Corporation, and include our consolidated subsidiaries where the context so requires. References to "Bank" refer to our subsidiary Umpqua Bank, an Oregon state-chartered commercial bank, and references to "Umpqua Investments" refer to our subsidiary Umpqua Investments, Inc., a registered broker-dealer and investment adviser. The Bank also has a wholly-owned subsidiary, Financial Pacific Leasing Inc., a commercial equipment leasing company. Pivotus Ventures, Inc., a wholly-owned subsidiary of Umpqua Holdings Corporation, focuses on advancing bank innovation by developing new bank platforms that could have a significant impact on the experience and economics of banking.

In preparing these condensed consolidated financial statements, the Company has evaluated events and transactions subsequent to March 31, 2018 for potential recognition or disclosure. In management's opinion, all accounting adjustments necessary to accurately reflect the financial position and results of operations on the accompanying financial statements have been made. These adjustments include normal and recurring accruals considered necessary for a fair and accurate presentation. The results for interim periods are not necessarily indicative of results for the full year or any other interim period. Certain reclassifications of prior period amounts have been made to conform to current classifications.

Application of new accounting guidance

As of January 1, 2018, Umpqua adopted the Financial Accounting Standard Board's ("FASB") Accounting Standard Update ("ASU") No. 2014-09, Revenue from Contracts with Customers and all subsequent amendments to the ASU (collectively "ASC 606"), which (i) creates a single framework for recognizing revenue from contracts with customers that are within its scope and (ii) revises when it is appropriate to recognize a gain or loss from the transfer of nonfinancial assets such as other real estate owned. The majority of Umpqua's revenues come from interest income and other sources, including loans, leases, securities, and derivatives, that are outside the scope of ASC 606. Umpqua's revenues that are within the scope of ASC 606 are presented within Non-Interest Income and are recognized as revenue as the Company satisfies its obligation to the customer. Revenues within the scope of ASC 606 include service charges on deposits, brokerage revenue, interchange income, and the sale of other real estate owned. Refer to Note 15 - Revenue from Contracts with Customers for further discussion of Umpqua's accounting policies for revenue sources within the scope of ASC 606.

Umpqua adopted ASC 606 using the modified retrospective method applied on all contracts not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under ASC 606 while prior period amounts continue to be reported in accordance with legacy generally accepted accounting principles ("GAAP"). The adoption of ASC 606 did not result in a material change to the accounting for any of the in-scope revenue streams; as such, no cumulative effect adjustment was recorded.

As of January 1, 2018, Umpqua applied FASB ASU No. 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The new guidance relates to the recognition and measurement of financial instruments. This ASU requires equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. Upon adoption, certain equity securities were reclassified from available for sale to the equity securities classification on the balance sheet. The ASU was applied prospectively. The amendment also requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements. This ASU also eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. The disclosures in the fair value footnote have been updated accordingly.

The amendment also requires a reporting organization to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument specific credit risk (also referred to as "own credit") when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The Company's junior subordinated debentures are variable-rate instruments based on LIBOR, with the majority reseting quarterly. Applying the updated guidance, the FASB noted that the entire risk in excess of the risk free or benchmark rate could be considered instrument-specific credit risk. The Company has determined that all changes in fair value of the junior subordinated debentures are due to changes in value other than in the benchmark rate, and accordingly are instrument-specific credit risk. As such, the Company calculated the change in the discounted cash flows based on updated market credit spreads since the election of the fair value option for each junior subordinated debenture measured at fair value to be a net gain of $13.0 million. The gain was recorded, net of the tax effect, as a cumulative effect adjustment between retained earnings and accumulated other comprehensive income (loss), resulting in an adjustment of $9.7 million upon adoption.

For the first quarter of 2018, the change in fair value is attributable to the change in the instrument specific credit risk of the junior subordinated debentures, as determined by the application of ASU 2016-01. Accordingly, the loss on fair value of junior subordinated debentures for the quarter ended March 31, 2018 of $1.7 million is recorded in other comprehensive income (loss), net of tax, as an other comprehensive loss of $1.3 million.