Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Earnings Per Share
Net income attributable to Sotheby's	$ 127,234	$ 86,239	$ 129,655	$ 84,062
Less: Net income attributable to participating securities	1,237	1,905	1,602	2,176
Net income attributable to Sotheby's common shareholders	125,997	84,334	128,053	81,886
Weighted average common shares outstanding	67,405	66,337	67,188	66,167
Basic earnings per share - Sotheby's common shareholders	$ 1.87	$ 1.27	$ 1.91	$ 1.24
Less: Net income attributable to participating securities	1,201	1,886	1,556	2,152
Net income attributable to Sotheby's common shareholders	$ 126,033	$ 84,353	$ 128,099	$ 81,910
Weighted average dilutive potential common shares outstanding	2,086	704	2,064	805
Denominator for calculation of diluted earnings per share	69,491	67,041	69,252	66,972
Diluted earnings per share - Sotheby's common shareholders	$ 1.81	$ 1.26	$ 1.85	$ 1.22

Earnings allocated to participating securities under the two-class method to the extent that participating securities may share in earnings as if all of the earnings for the period had been distributed.

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The amount of net income or loss for the period per each share of common stock outstanding during the reporting period.

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The amount of net income or loss for the period per each share of common stock and dilutive common stock equivalents outstanding during the reporting period.

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The portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent. If the entity does not present consolidated financial statements, the amount of profit or loss for the period, net of income taxes.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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Net Income (Loss) Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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The sum of dilutive potential common shares used in the calculation of the diluted per-share computation.

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The average number of shares issued and outstanding that are used in calculating diluted EPS, determined based on the timing of issuance of shares in the period.

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Number of [basic] shares, after adjustment for contingently issuable shares and other shares not deemed outstanding, determined by relating the portion of time within a reporting period that common shares have been outstanding to the total time in that period.

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