Represents the amount of guarantees advanced to a consignor prior to the sale date as of the balance sheet date.

No definition available.

Name:	bid_AuctionGuaranteeAdvancesOutstanding
Namespace Prefix:	bid_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Charge to General & Administrative Expense as a result of an accomodation made to an irrevocable bid client.

+ References

No definition available.

+ Details

Name:	bid_ClientGoodwillGesture
Namespace Prefix:	bid_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Contractual risk and reward sharing arrangements under which a counterparty commits to bid a predetermined price on the guaranteed property.

+ References

No definition available.

+ Details

Name:	bid_IrrevocableBids
Namespace Prefix:	bid_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the maximum amount of net auction of guarantees permissible as per the covenants contained within the entity's covenants revolving credit agreement.

+ References

No definition available.

+ Details

Name:	bid_MaximumAmountofNetAuctionGuaranteesPermissible
Namespace Prefix:	bid_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

+ Details

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of guarantee, including, but not limited to, financial standby letter of credit, fair value guarantee, guarantee of collection of scheduled contractual cash flows from financial assets, and contracts that contingently require the guarantor to make payments or perform services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12201-110248

+ Details

Name:	us-gaap_GuaranteesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=bid_AgencyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Auction Guarantees (Details) (USD $)	3 Months Ended
Auction Guarantees (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Feb. 25, 2015
Client Goodwill Gesture	$ 1,700,000bid_ClientGoodwillGesture
Maximum Amount of Net Auction Guarantees Permissible		600,000,000
Outstanding guarantee maximum exposure		148,300,000
Irrevocable Bids		42,000,000bid_IrrevocableBids
Estimated fair value of obligation to perform under auction guarantees		5,300,000us-gaap_GuaranteesFairValueDisclosure	2,900,000us-gaap_GuaranteesFairValueDisclosure
Subsequent Event [Member]
Outstanding guarantee maximum exposure				79,500,000
Irrevocable Bids				28,200,000
Agency [Member]
Guarantee advances		$ 25,000,000	$ 28,000,000