Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013
Assets:
Fixed income securities, at fair value (amortized cost of $5,868,458 in 2014 and $5,927,254 in 2013)	$ 6,100,431		$ 5,885,316
Fixed income securities pledged as collateral, at fair value (amortized cost of $65,027 in 2014 and $126,196 in 2013)	65,029		126,223
Short-term investments, at fair value (amortized cost of $344,187 in 2014 and $271,118 in 2013)	344,187		271,119
Other investments, at fair value	256,455		241,069
Total investments	6,766,102		6,523,727
Cash and Cash Equivalents, at Carrying Value	74,461		77,370
Receivable for securities	31,107		14,450
Investment income due and accrued	34,518		37,663
Premium receivables	1,356,362		1,453,021
Reinsurance recoverable on paid and unpaid losses	109,255		121,249
Deferred ceded premium	134,278		145,529
Subrogation recoverable	484,152		498,478
Loans	6,349		6,179
Derivative assets	89,680		77,711
Insurance intangible asset	1,549,384		1,597,965
Goodwill	514,511		514,511
Other assets	127,898		35,927
Variable interest entity assets:
Fixed income securities, at fair value	6,100,431		5,885,316
Investment income due and accrued	34,518		37,663
Other assets	127,898		35,927
Total assets	27,723,353		27,092,477
Liabilities:
Unearned premiums	2,070,312		2,255,680
Loss and loss expense reserves	6,072,323		5,968,712
Ceded premiums payable	64,740		70,962
Obligations under investment agreements	169,582		359,070
Deferred taxes	2,314		2,199
Current taxes	0		738
Long-term debt	981,424		963,178
Accrued interest payable	339,975		294,817
Derivative liabilities	342,273		253,898
Other liabilities	60,086		67,377
Payable for securities purchased	15,358		4,654
Variable interest entity liabilities:
Accrued interest payable	339,975		294,817
Long-term debt, at fair value	981,424		963,178
Derivative liabilities	342,273		253,898
Other liabilities	60,086		67,377
Total liabilities	26,499,822		26,114,055
Stockholders’ equity:
Preferred stock, par value $0.01 per share; authorized shares—20,000,000; issued and outstanding shares—none	0		0
Common stock, par value $0.01 per share; authorized shares—130,000,000; issued and outstanding shares—45,003,512 at June 30, 2014 and 45,003,461 at December 31, 2013	450		450
Additional paid-in capital	188,060		185,672
Accumulated other comprehensive income	306,328		11,661
Accumulated earnings	453,256		505,219
Common stock held in treasury at cost, 937 shares at June 30, 2014 and December 31, 2013	(19)		(19)
Total Ambac Financial Group, Inc. stockholders’ equity	948,075		702,983
Noncontrolling interest	275,456		275,439
Total stockholders’ equity	1,223,531		978,422
Total liabilities and stockholders’ equity	27,723,353		27,092,477
Variable Interest Entity [Member]
Assets:
Fixed income securities, at fair value (amortized cost of $5,868,458 in 2014 and $5,927,254 in 2013)	2,688,388		2,475,182
Investment income due and accrued	1,409		1,365
Other assets	3,068		19,617
Variable interest entity assets:
Fixed income securities, at fair value	2,688,388		2,475,182
Restricted cash	7,712		17,498
Investment income due and accrued	1,409		1,365
Loans, at fair value	13,743,231		13,398,895
Intangible assets	0		76,140
Other assets	3,068		19,617
Liabilities:
Long-term debt	14,450,434		14,091,753
Accrued interest payable	3,353		722
Derivative liabilities	1,927,460		1,772,306
Other liabilities	188		7,989
Variable interest entity liabilities:
Accrued interest payable	3,353		722
Long-term debt, at fair value	14,450,434		14,091,753
Derivative liabilities	1,927,460		1,772,306
Other liabilities	188		7,989
Successor [Member]
Assets:
Cash and Cash Equivalents, at Carrying Value	74,461		77,370
Income Taxes Receivable, Current		1,488
Derivative assets	89,680		77,711
Variable interest entity assets:
Total assets	27,723,353
Liabilities:
Derivative liabilities	342,273		253,898
Variable interest entity liabilities:
Derivative liabilities	342,273		253,898
Stockholders’ equity:
Accumulated other comprehensive income	306,328	104,417	11,661
Total stockholders’ equity	$ 1,223,531		$ 978,422