Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	2 Months Ended	4 Months Ended	6 Months Ended
	Jun. 30, 2013 Successor Ambac [Member]	Apr. 30, 2013 Predecessor Ambac [Member]	Jun. 30, 2012 Predecessor Ambac [Member]
Cash flows from operating activities:
Net income (loss) attributable to common shareholders	$ 205,681	$ 3,349,049	$ (557,798)
Noncontrolling interest in subsidiaries' earnings	(399)	(1,771)	(2,230)
Net income (loss)	205,282	3,347,278	(560,028)
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	501	974	1,546
Amortization of bond premium and discount	(3,240)	(60,146)	(121,602)
Reorganization items	424	(2,745,180)	3,228
Deferred income taxes	(16)	(6)
Current income taxes	186	(101,188)	1,043
Deferred acquisition costs		14,207	11,603
Unearned premiums, net	(102,460)	(172,549)	(295,016)
Losses and loss expenses, net	(34,763)	(43,284)	771,247
Ceded premiums payable	(3,033)	(2,059)	(17,276)
Investment income due and accrued	2,243	1,781	2,677
Premium receivables	66,733	88,990	198,605
Accrued interest payable	15,511	23,953	53,425
Amortization of intangible assets	24,952
Net mark-to-market (gains) losses	(45,146)	63,828	20,964
Net realized investment gains	(18,472)	(53,305)	(67,459)
Losses on extinguishment of debt			177,745
Other-than-temporary impairment charges	2,002	467	5,399
Variable interest entity activities	(4,598)	(426,566)	(20,756)
Other, net	(66,543)	62,122	(129,916)
Net cash provided by operating activities	39,563	(683)	35,429
Cash flows from investing activities:
Proceeds from sales of bonds	343,040	310,916	427,281
Proceeds from matured bonds	182,304	307,472	521,807
Purchases of bonds	(746,914)	(286,633)	(448,691)
Proceeds from sales of other invested assets	1,228	(164,368)
Purchases of other invested assets	(79,596)
Change in short-term investments	115,437	(64,956)	(226,988)
Loans, net	230	1,920	8,843
Change in swap collateral receivable	10,889	(8,863)	26,391
Other, net	4,678	19,828	(7,343)
Net cash used in investing activities	(168,704)	115,316	301,300
Cash flows from financing activities:
Paydowns of variable interest entity secured borrowing	(3,310)	(5,519)	(10,636)
Proceeds from warrant exercise	15
Payments for investment and repurchase agreement draws			(104,634)
Payments for extinguishment of long-term debt			(188,446)
Net cash used in financing activities	(3,295)	(5,519)	(303,716)
Net cash flow	(132,436)	109,114	33,013
Cash at beginning on period	152,951	43,837	15,999
Cash at ending of period	20,515	152,951	49,012
Supplemental disclosure of cash flow information:
Income taxes	336	102,129
Interest on variable interest entity secured borrowing	90	276	927
Interest on investment agreements	203	1,726	4,570
Cash receipts and payments related to reorganization items:
Professional fees paid for services rendered in connection with the Chapter 11 proceeding	$ 795	$ 3,860	$ 6,956