Derivative Instruments - Summary of Location and Amount of Gains and Losses of Derivative Contracts (Detail) (USD $) In Thousands, unless otherwise specified	2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	1 Months Ended
	Jun. 30, 2013 Successor Ambac [Member]	Jun. 30, 2014 Successor Ambac [Member]	Apr. 30, 2013 Successor Ambac [Member]	Jun. 30, 2014 Successor Ambac [Member]	Jun. 30, 2013 Successor Ambac [Member] Variable Interest Entity [Member]	Jun. 30, 2014 Successor Ambac [Member] Variable Interest Entity [Member]	Apr. 30, 2013 Successor Ambac [Member] Variable Interest Entity [Member]	Jun. 30, 2014 Successor Ambac [Member] Variable Interest Entity [Member]	Jun. 30, 2013 Successor Ambac [Member] Financial Services Derivatives Products [Member]	Jun. 30, 2014 Successor Ambac [Member] Financial Services Derivatives Products [Member]	Apr. 30, 2013 Successor Ambac [Member] Financial Services Derivatives Products [Member]	Jun. 30, 2014 Successor Ambac [Member] Financial Services Derivatives Products [Member]	Jun. 30, 2013 Successor Ambac [Member] Credit Derivatives [Member] Financial Guarantee [Member] Net Change in Fair Value of Credit Derivatives [Member]	Jun. 30, 2014 Successor Ambac [Member] Credit Derivatives [Member] Financial Guarantee [Member] Net Change in Fair Value of Credit Derivatives [Member]	Apr. 30, 2013 Successor Ambac [Member] Credit Derivatives [Member] Financial Guarantee [Member] Net Change in Fair Value of Credit Derivatives [Member]	Jun. 30, 2014 Successor Ambac [Member] Credit Derivatives [Member] Financial Guarantee [Member] Net Change in Fair Value of Credit Derivatives [Member]	Jun. 30, 2013 Successor Ambac [Member] Interest Rate Swaps [Member] Income on Variable Interest Entities [Member] Variable Interest Entity [Member]	Jun. 30, 2014 Successor Ambac [Member] Interest Rate Swaps [Member] Income on Variable Interest Entities [Member] Variable Interest Entity [Member]	Apr. 30, 2013 Successor Ambac [Member] Interest Rate Swaps [Member] Income on Variable Interest Entities [Member] Variable Interest Entity [Member]	Jun. 30, 2014 Successor Ambac [Member] Interest Rate Swaps [Member] Income on Variable Interest Entities [Member] Variable Interest Entity [Member]	Jun. 30, 2013 Successor Ambac [Member] Interest Rate Swaps [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Jun. 30, 2014 Successor Ambac [Member] Interest Rate Swaps [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Apr. 30, 2013 Successor Ambac [Member] Interest Rate Swaps [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Jun. 30, 2014 Successor Ambac [Member] Interest Rate Swaps [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Jun. 30, 2013 Successor Ambac [Member] Currency Swaps [Member] Income on Variable Interest Entities [Member] Variable Interest Entity [Member]	Jun. 30, 2014 Successor Ambac [Member] Currency Swaps [Member] Income on Variable Interest Entities [Member] Variable Interest Entity [Member]	Apr. 30, 2013 Successor Ambac [Member] Currency Swaps [Member] Income on Variable Interest Entities [Member] Variable Interest Entity [Member]	Jun. 30, 2014 Successor Ambac [Member] Currency Swaps [Member] Income on Variable Interest Entities [Member] Variable Interest Entity [Member]	Jun. 30, 2013 Successor Ambac [Member] Futures Contracts [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Jun. 30, 2014 Successor Ambac [Member] Futures Contracts [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Apr. 30, 2013 Successor Ambac [Member] Futures Contracts [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Jun. 30, 2014 Successor Ambac [Member] Futures Contracts [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Jun. 30, 2013 Successor Ambac [Member] Other Contracts [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Jun. 30, 2014 Successor Ambac [Member] Other Contracts [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Apr. 30, 2013 Successor Ambac [Member] Other Contracts [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Jun. 30, 2014 Successor Ambac [Member] Other Contracts [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Apr. 30, 2013 Predecessor [Member]	Apr. 30, 2013 Predecessor [Member] Variable Interest Entity [Member]	Apr. 30, 2013 Predecessor [Member] Financial Services Derivatives Products [Member]	Apr. 30, 2013 Predecessor [Member] Credit Derivatives [Member] Financial Guarantee [Member] Net Change in Fair Value of Credit Derivatives [Member]	Apr. 30, 2013 Predecessor [Member] Interest Rate Swaps [Member] Income on Variable Interest Entities [Member] Variable Interest Entity [Member]	Apr. 30, 2013 Predecessor [Member] Interest Rate Swaps [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Apr. 30, 2013 Predecessor [Member] Currency Swaps [Member] Income on Variable Interest Entities [Member] Variable Interest Entity [Member]	Apr. 30, 2013 Predecessor [Member] Futures Contracts [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]	Apr. 30, 2013 Predecessor [Member] Other Contracts [Member] Financial Services Derivatives Products [Member] Derivative Products [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Derivative instruments, gain (loss) recognized in income, net, Total	$ 570,667	$ (131,974)	$ (297,855)	$ (250,817)	$ 435,734	$ (82,770)	$ (203,736)	$ (155,154)	$ 83,713	$ (47,985)	$ (33,735)	$ (101,826)	$ 51,220	$ (1,219)	$ (60,384)	$ 6,163	$ 437,624	$ (81,773)	$ (203,620)	$ (159,565)	$ 74,169	$ (45,534)	$ (30,622)	$ (97,394)	$ (1,890)	$ (997)	$ (116)	$ 4,411	$ 9,831	$ (2,477)	$ (3,133)	$ (4,469)	$ (287)	$ 26	$ 20	$ 37	$ (214,229)	$ (107,892)	$ (33,166)	$ (73,171)	$ (103,072)	$ (29,600)	$ (4,820)	$ (3,588)	$ 22