This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Article 5

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This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses and taxes from ongoing operations before extraordinary items, and noncontrolling interest.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 19

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- Definition

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

+ References

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))

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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Amount before tax of reclassification adjustment from accumulated other comprehensive (income) loss for prior service cost (credit) related to pension and other postretirement benefit plans.

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Amount before tax of reclassification adjustment from accumulated other comprehensive income (loss) for actuarial gain (loss) related to pension and other postretirement benefit plans.

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Comprehensive Income - Schedule of Amounts Reclassed Out of Each Component of Accumulated Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	4 Months Ended	9 Months Ended	4 Months Ended			3 Months Ended	5 Months Ended	3 Months Ended	5 Months Ended	3 Months Ended	5 Months Ended
	Sep. 30, 2012 Predecessor Ambac [Member]	Apr. 30, 2013 Predecessor Ambac [Member]	Sep. 30, 2012 Predecessor Ambac [Member]	Apr. 30, 2013 Predecessor Ambac [Member] Reclassification out of Accumulated Other Comprehensive Income [Member]	Apr. 30, 2013 Predecessor Ambac [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Unrealized Gains (Losses) on Available-for-Sale Securities [Member]	Apr. 30, 2013 Predecessor Ambac [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Amortization of Postretirement Benefit [Member]	Sep. 30, 2013 Successor Ambac [Member]	Sep. 30, 2013 Successor Ambac [Member]	Sep. 30, 2013 Successor Ambac [Member] Reclassification out of Accumulated Other Comprehensive Income [Member]	Sep. 30, 2013 Successor Ambac [Member] Reclassification out of Accumulated Other Comprehensive Income [Member]	Sep. 30, 2013 Successor Ambac [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Unrealized Gains (Losses) on Available-for-Sale Securities [Member]	Sep. 30, 2013 Successor Ambac [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service cost						$ (1,616)
Net realized investment gains					12,865						(49,561)	(33,089)
Actuarial gains (losses)						727
Total before tax						(889)
Tax (expense) benefit	667	755	756			(704)	594	1,107
Net of tax and noncontrolling interest				$ (12,680)	$ 12,865	$ (185)			$ 49,561	$ 33,089	$ (49,561)	$ (33,089)