Net Income Per Share - Additional Information (Detail) (USD $)	5 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013 Successor Ambac [Member]	Apr. 30, 2013 Successor Ambac [Member]
Schedule Of Earnings Per Share [Line Items]
Number of new common stock issued	45,000,000	45,000,000	45,002,524	45,000,000
Par value of common stock issued	$ 0.01	$ 0.01	$ 0.01
Number of warrants issued	5,047,138	5,047,138		5,047,138
Number of shares exercisable for warrants	5,047,138	5,047,138
Exercise price of common stock	16.67	16.67
Expiry date of warrants		Apr. 30, 2023
Warrant exercised	6,312
Common stock shares issued	2,524
Warrants outstanding			5,040,826