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Business and Risks (Narrative) (Detail) (USD $)	9 Months Ended							0 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 Mbia Inc [Member]	Dec. 31, 2013 Mbia Inc [Member]	Sep. 30, 2014 Mbia Inc General Corporate Purposes [Member]	Dec. 31, 2013 Mbia Inc General Corporate Purposes [Member]	Sep. 30, 2014 Asset Liability Products Segment [Member]	Dec. 31, 2013 Asset Liability Products Segment [Member]	Oct. 03, 2014 National [Member] SubsequentEvent [Member]
Business Acquisition [Line Items]
Number of operating segments	3
Dividends from subsidiaries								$ 220,000,000
Liquid assets		348,000,000	359,000,000	297,000,000	307,000,000	51,000,000	52,000,000
Amount released from tax escrow account	220,000,000
Commuted gross insured exposure	$ 6,500,000,000

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This element represents the liquidity position of the entity

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- Definition

This element represents the amount released from the escrow account related to the tax sharing agreement during the period

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- Definition

This element represents disclosure of the aggregate cash dividends paid to the entity by consolidated subsidiaries.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 235

-Section S99

-Paragraph 2

-Subparagraph (SX 210.9-06)

-URI http://asc.fasb.org/extlink&oid=6882215&loc=d3e537971-122884



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 06

-Article 9



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph b

-Article 12



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 3

-Subparagraph (SX 210.12-04.(b))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

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- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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