Quarterly Results (Unaudited) (Schedule Of Quarterly Results) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014 principal_selling_season	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 principal_selling_season	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Number of principal selling seasons	2								2
Q2 and Q4 Net Auction Sales as Percentage of Total Net Auction Sales	83.00%		79.00%
Auction Commission Revenues as Percentage of Total Revenues									81.00%	81.00%
Net Auction Sales	$ 2,122,738	$ 322,973	$ 1,971,338	$ 734,370	$ 1,932,887	$ 228,587	$ 1,654,088	$ 523,386
Agency	309,582	76,229	316,187	123,128	327,592	76,929	294,943	94,175	825,126	793,639	717,231
Principal	28,951	6,273	8,733	26,001	5,619	23,491	2,122	1,083	69,958	30,638	26,180
Finance	10,274	8,917	8,140	5,682	3,942	5,164	5,561	4,933	33,013	21,277	17,707
License fees	1,949	2,376	2,462	1,697	1,724	1,902	2,090	1,186	8,484	6,902	6,124
Other	468	406	295	303	324	378	152	368	1,472	1,222	1,250
Revenues	351,224	94,201	335,817	156,811	339,201	107,864	304,868	101,745	938,053	853,678	768,492
Net (loss) income attributable to Sotheby's	$ 74,003	$ (27,726)	$ 77,632	$ (6,114)	$ 90,753	$ (30,131)	$ 91,729	$ (22,345)	$ 117,795	$ 130,006	$ 108,292
Basic earnings (loss) per share - Sotheby’s common shareholders (usd per share)	$ 1.07	$ (0.40)	$ 1.12	$ (0.09)	$ 1.32	$ (0.44)	$ 1.34	$ (0.33)	$ 1.69	$ 1.90	$ 1.59
Diluted earnings (loss) per share - Sotheby’s common shareholders (usd per share)	$ 1.06	$ (0.40)	$ 1.11	$ (0.09)	$ 1.30	$ (0.44)	$ 1.33	$ (0.33)	$ 1.68	$ 1.88	$ 1.57
Weighted average basic shares outstanding (shares)	68,992	68,990	68,938	69,143	68,876	68,361	68,306	67,951	69,016	68,374	67,691
Weighted average diluted shares outstanding (shares)	69,707	68,990	69,491	69,143	69,826	68,361	68,889	67,951	69,606	69,175	68,527