Income Taxes - Effect of Income Taxes on Net Income and Stockholders' Equity (Detail) (USD $) In Thousands, unless otherwise specified	8 Months Ended	4 Months Ended	12 Months Ended
Dec. 31, 2013 Successor Ambac [Member]	Apr. 30, 2013 Predecessor Ambac [Member]	Dec. 31, 2012 Predecessor Ambac [Member]
Pre-tax from continuing operations [Line Items]
Total income taxes charged to net income	$ 7,514	$ 755	$ 2,849
Income taxes charged (credited) to stockholders' equity:
Unrealized gains (losses) on investment securities	284	(204,145)	18,448
Valuation Allowance to Equity	(284)	204,145	(18,448)
Other
Total charged to stockholders' equity:
Total effect of income taxes	$ 7,514	$ 755	$ 2,849

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Article 4

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Income Tax Expense (or Benefit)

-URI http://asc.fasb.org/extlink&oid=6515339

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a),(b)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration