Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Assets:
Fixed income securities, at fair value (amortized cost of $4,945,921 in 2012 and $5,346,897 in 2011)	$ 5,390,290	$ 5,830,289
Fixed income securities pledged as collateral, at fair value (amortized cost of $286,115 in 2012 and $261,958 in 2011)	286,660	263,530
Short-term investments (amortized cost of $1,009,868 in 2012 and $783,015 in 2011)	1,010,059	783,071
Other (approximates fair value)	100	100
Total investments	6,687,109	6,876,990
Cash	49,012	15,999
Restricted cash	2,500	2,500
Receivable for securities	112,013	38,164
Investment income due and accrued	42,651	45,328
Premium receivables	1,829,874	2,028,479
Reinsurance recoverable on paid and unpaid losses	169,961	159,902
Deferred ceded premium	197,437	221,303
Subrogation recoverable	442,097	659,810
Deferred acquisition costs	211,907	223,510
Loans	10,153	18,996
Derivative assets	132,914	175,207
Other assets	103,804	104,300
Total assets	26,611,791	27,113,695
Liabilities:
Liabilities subject to compromise	1,707,411	1,707,421
Unearned premiums	3,138,275	3,457,157
Losses and loss expense reserve	7,607,663	7,044,070
Ceded premiums payable	98,279	115,555
Obligations under investment agreements	424,840	523,046
Obligations under investment repurchase agreements	18,276	23,500
Current taxes	96,752	95,709
Long-term debt	144,036	223,601
Accrued interest payable	192,984	170,169
Derivative liabilities	394,040	414,508
Other liabilities	94,678	107,441
Payable for securities purchased	5,328	1,665
Total liabilities	30,367,170	30,263,228
Stockholders' deficit:
Preferred stock
Common stock	3,080	3,080
Additional paid-in capital	2,172,027	2,172,027
Accumulated other comprehensive income	417,593	463,259
Accumulated deficit	(6,598,384)	(6,039,922)
Treasury Stock, Value	(410,755)	(411,419)
Total Ambac Financial Group, Inc. stockholders' deficit	(4,416,439)	(3,812,975)
Noncontrolling interest	661,060	663,442
Total stockholders' deficit	(3,755,379)	(3,149,533)
Total liabilities and stockholders' deficit	26,611,791	27,113,695
Variable interest entity
Assets:
Fixed income securities, at fair value (amortized cost of $4,945,921 in 2012 and $5,346,897 in 2011)	2,162,062	2,199,338
Restricted cash	2,276	2,140
Investment income due and accrued	4,034	4,032
Loans	14,446,047	14,329,515
Other assets	5,940	8,182
Liabilities:
Long-term debt	14,376,872	14,288,540
Accrued interest payable	3,645	3,490
Derivative liabilities	2,063,809	2,087,052
Other liabilities	$ 282	$ 304