Reorganization Under Chapter 11 - Summary of Reorganization Items in Consolidated Statements of Total Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		5 Months Ended	9 Months Ended	4 Months Ended
	Sep. 30, 2014 Successor Ambac [Member]	Sep. 30, 2013 Successor Ambac [Member]	Sep. 30, 2013 Successor Ambac [Member]	Sep. 30, 2014 Successor Ambac [Member]	Apr. 30, 2013 Predecessor Ambac [Member]
Fresh-Start Adjustment [Line Items]
U.S. Trustee fees	$ 0	$ 13	$ 13	$ 0	$ 23
Professional fees	2	(9)	415	211	4,483
Debtor Reorganization Items, Gain (Loss) on Settlement of Other Claims, Net	0	0	0	0	(1,521,435)
Fresh Start Adjustments	0	0	0	0	(1,228,251)
Total reorganization items	$ 2	$ 4	$ 428	$ 211	$ (2,745,180)