Basis of Presentation	3 Months Ended
Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation Accounting Principles—The unaudited Condensed Consolidated Financial Statements included herein have been prepared by the management of Sotheby’s (or the "Company") in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") and pursuant to the rules and regulations of the Securities and Exchange Commission (the "SEC"). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. In our opinion, the unaudited Condensed Consolidated Financial Statements reflect all adjustments of a normal recurring nature that are necessary for a fair presentation of the results for the interim periods presented. Interim results are not necessarily indicative of results for a full year (see Note 2). We urge you to read these Condensed Consolidated Financial Statements in conjunction with the information included in our 2016 Form 10-K filed with the SEC on February 27, 2017. Principles of Consolidation—The unaudited Condensed Consolidated Financial Statements include the accounts of our wholly-owned subsidiaries and Sotheby's (Beijing) Auction Co., Ltd. ("Sotheby's Beijing"), a joint venture in which we have a controlling 80% ownership interest. The net income (loss) attributable to the minority owner of Sotheby's Beijing is reported as "Net Income (Loss) Attributable to Noncontrolling Interest" in our Condensed Consolidated Statements of Operations and the non-controlling 20% ownership interest is reported as "Noncontrolling Interest" within the Equity section of our Condensed Consolidated Balance Sheets. Intercompany transactions and balances among our subsidiaries are eliminated in consolidation. Equity investments through which we exercise significant influence over the investee, but do not control, are accounted for using the equity method. Under the equity method, our share of investee earnings or losses is recorded within Equity in Earnings of Investees in our Condensed Consolidated Statements of Operations. Our interest in the net assets of these equity method investees is recorded within Other Long-Term Assets on our Condensed Consolidated Balance Sheets. Our equity method investees include Acquavella Modern Art (see Note 22), a partnership through which a collection of fine art is being sold, and RM Sotheby's, an auction house for investment-quality automobiles. Estimates and Assumptions—The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Adoption of Accounting Standards Update ("ASU") 2016-09—In March 2016, the Financial Accounting Standards Board (the "FASB") issued ASU 2016-09, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting. ASU 2016-09 simplifies several aspects of the accounting and presentation of share-based payment transactions, including the accounting for the related income tax consequences and certain classifications within the statement of cash flows. We adopted ASU 2016-09 on its effective date of January 1, 2017. ASU 2016-09 requires that all excess tax benefits and deficiencies resulting from the vesting of share-based payments be recorded in the statement of operations, whereas previous guidance generally permitted such items to be recorded in the equity section of the balance sheet provided that an adequate level of previously recorded excess tax benefits existed. We adopted this aspect of ASU 2016-09 on a prospective basis beginning on January 1, 2017. The adoption of ASU 2016-09 and the vesting of certain share-based payments in the first quarter of 2017 resulted in the recording of a $2.6 million income tax benefit in our Condensed Consolidated Statements of Operations, which increased our effective income tax benefit rate for the period by approximately 14%. Under previous guidance, this income tax benefit would have been recorded as an increase to Additional Paid-In Capital on our Condensed Consolidated Balance Sheets. ASU 2016-09 also changed how excess tax benefits resulting from the vesting of share-based payments are presented in the statement of cash flows. ASU 2016-09 requires that such excess tax benefits be classified within Operating Activities along with other income tax cash flows. Under previous guidance, excess tax benefits resulting from the vesting of share-based payments were presented as a cash inflow within Financing Activities and a corresponding cash outflow within Operating Activities. The adoption of ASU 2016-09 in the first quarter of 2017 resulted in the classification of $2.6 million of excess tax benefits within Operating Activities in our Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2017. The retrospective adoption of ASU 2016-09 did not have an effect on our Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2016 because no excess tax benefits were recorded in that period. The adoption of the other aspects of ASU 2016-09 did not have a material impact on our Condensed Consolidated Financial Statements as of and for the three months ended March 31, 2017 and 2016. Adoption of Other Recently Issued Accounting Standards—In March 2016, the FASB issued ASU 2016-05, Derivatives and Hedging: Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships, which clarifies that a change in the counterparty to a derivative instrument that has been designated as a hedging instrument would not, in and of itself, be considered a termination of the derivative instrument, provided that all other hedge accounting criteria continue to be met. The adoption of ASU 2016-05 on its effective date of January 1, 2017 did not have a material effect on our Condensed Consolidated Financial Statements as of and for the three months ended March 31, 2017 and 2016. In March 2016, the FASB issued ASU 2016-06, Derivatives and Hedging - Contingent Put and Call Options in Debt Instruments, which aims to reduce the diversity of practice in identifying embedded derivatives in debt instruments. ASU 2016-06 clarifies that the nature of an exercise contingency is not subject to the “clearly and closely” criteria for purposes of assessing whether the call or put option must be separated from the debt instrument and accounted for separately as a derivative. The adoption of ASU 2016-06 on its effective date of January 1, 2017 did not have a material effect on our Condensed Consolidated Financial Statements as of and for the three months ended March 31, 2017 and 2016.

Basis of Presentation

Accounting Principles—The unaudited Condensed Consolidated Financial Statements included herein have been prepared by the management of Sotheby’s (or the "Company") in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") and pursuant to the rules and regulations of the Securities and Exchange Commission (the "SEC"). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. In our opinion, the unaudited Condensed Consolidated Financial Statements reflect all adjustments of a normal recurring nature that are necessary for a fair presentation of the results for the interim periods presented. Interim results are not necessarily indicative of results for a full year (see Note 2). We urge you to read these Condensed Consolidated Financial Statements in conjunction with the information included in our 2016 Form 10-K filed with the SEC on February 27, 2017.

Principles of Consolidation—The unaudited Condensed Consolidated Financial Statements include the accounts of our wholly-owned subsidiaries and Sotheby's (Beijing) Auction Co., Ltd. ("Sotheby's Beijing"), a joint venture in which we have a controlling 80% ownership interest. The net income (loss) attributable to the minority owner of Sotheby's Beijing is reported as "Net Income (Loss) Attributable to Noncontrolling Interest" in our Condensed Consolidated Statements of Operations and the non-controlling 20% ownership interest is reported as "Noncontrolling Interest" within the Equity section of our Condensed Consolidated Balance Sheets. Intercompany transactions and balances among our subsidiaries are eliminated in consolidation.

Equity investments through which we exercise significant influence over the investee, but do not control, are accounted for using the equity method. Under the equity method, our share of investee earnings or losses is recorded within Equity in Earnings of Investees in our Condensed Consolidated Statements of Operations. Our interest in the net assets of these equity method investees is recorded within Other Long-Term Assets on our Condensed Consolidated Balance Sheets. Our equity method investees include Acquavella Modern Art (see Note 22), a partnership through which a collection of fine art is being sold, and RM Sotheby's, an auction house for investment-quality automobiles.

Estimates and Assumptions—The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Adoption of Accounting Standards Update ("ASU") 2016-09—In March 2016, the Financial Accounting Standards Board (the "FASB") issued ASU 2016-09, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting. ASU 2016-09 simplifies several aspects of the accounting and presentation of share-based payment transactions, including the accounting for the related income tax consequences and certain classifications within the statement of cash flows. We adopted ASU 2016-09 on its effective date of January 1, 2017.

ASU 2016-09 requires that all excess tax benefits and deficiencies resulting from the vesting of share-based payments be recorded in the statement of operations, whereas previous guidance generally permitted such items to be recorded in the equity section of the balance sheet provided that an adequate level of previously recorded excess tax benefits existed. We adopted this aspect of ASU 2016-09 on a prospective basis beginning on January 1, 2017. The adoption of ASU 2016-09 and the vesting of certain share-based payments in the first quarter of 2017 resulted in the recording of a $2.6 million income tax benefit in our Condensed Consolidated Statements of Operations, which increased our effective income tax benefit rate for the period by approximately 14%. Under previous guidance, this income tax benefit would have been recorded as an increase to Additional Paid-In Capital on our Condensed Consolidated Balance Sheets.

ASU 2016-09 also changed how excess tax benefits resulting from the vesting of share-based payments are presented in the statement of cash flows. ASU 2016-09 requires that such excess tax benefits be classified within Operating Activities along with other income tax cash flows. Under previous guidance, excess tax benefits resulting from the vesting of share-based payments were presented as a cash inflow within Financing Activities and a corresponding cash outflow within Operating Activities. The adoption of ASU 2016-09 in the first quarter of 2017 resulted in the classification of $2.6 million of excess tax benefits within Operating Activities in our Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2017. The retrospective adoption of ASU 2016-09 did not have an effect on our Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2016 because no excess tax benefits were recorded in that period.

The adoption of the other aspects of ASU 2016-09 did not have a material impact on our Condensed Consolidated Financial Statements as of and for the three months ended March 31, 2017 and 2016.

Adoption of Other Recently Issued Accounting Standards—In March 2016, the FASB issued ASU 2016-05, Derivatives and Hedging: Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships, which clarifies that a change in the counterparty to a derivative instrument that has been designated as a hedging instrument would not, in and of itself, be considered a termination of the derivative instrument, provided that all other hedge accounting criteria continue to be met. The adoption of ASU 2016-05 on its effective date of January 1, 2017 did not have a material effect on our Condensed Consolidated Financial Statements as of and for the three months ended March 31, 2017 and 2016.

In March 2016, the FASB issued ASU 2016-06, Derivatives and Hedging - Contingent Put and Call Options in Debt Instruments, which aims to reduce the diversity of practice in identifying embedded derivatives in debt instruments. ASU 2016-06 clarifies that the nature of an exercise contingency is not subject to the “clearly and closely” criteria for purposes of assessing whether the call or put option must be separated from the debt instrument and accounted for separately as a derivative. The adoption of ASU 2016-06 on its effective date of January 1, 2017 did not have a material effect on our Condensed Consolidated Financial Statements as of and for the three months ended March 31, 2017 and 2016.