Segment Reporting (Schedule Of Revenue And (Loss) Income Before Taxes by Segment) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting [Line Items]
Revenues	$ 351,224,000	$ 94,201,000	$ 335,817,000	$ 156,811,000	$ 339,201,000	$ 107,864,000	$ 304,868,000	$ 101,745,000	$ 938,053,000		$ 853,678,000		$ 768,492,000
Interest income									1,883,000		2,801,000		1,550,000
Interest expense									35,189,000	[1]	42,712,000	[1]	44,429,000
Depreciation and amortization									20,575,000		19,435,000		17,942,000
Segment income (loss) before taxes									193,021,000		185,693,000		159,436,000
Intercompany Charge									2,100,000		2,700,000		1,700,000
Agency [Member]
Segment Reporting [Line Items]
Revenues									825,126,000		794,179,000		717,231,000
Interest income									1,857,000		3,860,000		2,465,000
Interest expense									35,189,000	[1]	42,636,000	[1]	44,425,000
Depreciation and amortization									20,110,000		19,072,000		17,325,000
Segment income (loss) before taxes									188,045,000		164,499,000		152,240,000
Principal [Member]
Segment Reporting [Line Items]
Interest income													6,000
Interest expense									0	[1]	0	[1]	4,000
Depreciation and amortization									298,000		202,000		463,000
Segment income (loss) before taxes									71,000		(4,827,000)		(1,423,000)
Finance [Member]
Segment Reporting [Line Items]
Interest income									18,000
Interest expense											67,000	[1]
Depreciation and amortization									130,000		125,000		120,000
Segment income (loss) before taxes									26,491,000	[2]	21,445,000	[2]	18,595,000	[2]
All Other [Member]
Segment Reporting [Line Items]
Interest income									8,000		31,000		0
Interest expense											9,000	[1]
Depreciation and amortization									37,000		36,000		34,000
Segment income (loss) before taxes									7,343,000		5,975,000		5,338,000
Reconciling Items [Member]
Segment Reporting [Line Items]
Revenues									(9,005,000)		(10,491,000)		(7,779,000)
Interest income									0		(1,090,000)	[3]	(921,000)	[3]
Segment income (loss) before taxes									$ (28,929,000)		$ (1,399,000)		$ (15,314,000)

[1] Borrowing costs related to the Finance Credit Agreement, which include interest and the amortization of fees, are reflected in the Consolidated Income Statements as the Cost of Finance Revenues (See Note 9).

[2] In 2014, 2013, and 2012, Finance segment income before taxes includes $2.1 million, $2.7 million, and $1.7 million, respectively, of intercompany charges from Sotheby's global treasury function. As the Finance segment continues to debt finance its loan portfolio, it is expected that these intercompany charges will decrease in the future. (See Notes 5 and 9 for information on the capital structure of the Finance segment and the debt financing of client loans.)

[3] In 2013 and 2012, the reconciling item related to Interest Income relates to charges from the Agency segment to the Finance segment for intercompany borrowing costs. Beginning in 2014, these charges are no longer applicable due to the debt financing of the Finance segment's loan portfolio. (See Notes 5 and 9 for information on the capital structure of the Finance segment and the debt financing of client loans.)