Financial Guarantee Insurance Contracts - Summarized Future Gross Undiscounted Premiums Expected to be Collected, and Future Expected Premiums Earned, Net of Reinsurance (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014
Insurance [Abstract]
Future premiums expected to be collected, June 30, 2014	$ 30,303
Future premiums expected to be collected, September 30, 2014	34,189
Future premiums expected to be collected, December 31, 2014	31,942
Future premiums expected to be collected, December 31, 2015	127,738
Future premiums expected to be collected, December 31, 2016	121,100
Future premiums expected to be collected, December 31, 2017	114,752
Future premiums expected to be collected, December 31, 2018	109,588
Future premiums expected to be collected, December 31, 2023	488,119
Future premiums expected to be collected, December 31, 2028	373,791
Future premiums expected to be collected, December 31, 2033	250,704
Future premiums expected to be collected, December 31, 2038	120,724
Future premiums expected to be collected, December 31, 2043	41,501
Future premiums expected to be collected, December 31, 2048	12,595
Future premiums expected to be collected, December 31, 2053	2,262
Future premiums expected to be collected, December 31, 2058	31
Future premiums expected to be collected, Total	1,859,339
Future expected premiums to be earned, net of reinsurance, June 30, 2014	46,925
Future expected premiums to be earned, net of reinsurance, September 30, 2014	45,450
Future expected premiums to be earned, net of reinsurance, December 31, 2014	44,000
Future expected premiums to be earned, net of reinsurance, December 31, 2015	164,127
Future expected premiums to be earned, net of reinsurance, December 31, 2016	151,279
Future expected premiums to be earned, net of reinsurance, December 31, 2017	140,766
Future expected premiums to be earned, net of reinsurance, December 31, 2018	131,819
Future expected premiums to be earned, net of reinsurance, December 31, 2023	548,548
Future expected premiums to be earned, net of reinsurance, December 31, 2028	375,657
Future expected premiums to be earned, net of reinsurance, December 31, 2033	225,360
Future expected premiums to be earned, net of reinsurance, December 31, 2038	101,581
Future expected premiums to be earned, net of reinsurance, December 31, 2043	34,429
Future expected premiums to be earned, net of reinsurance, December 31, 2048	12,126
Future expected premiums to be earned, net of reinsurance, December 31, 2053	3,334
Future expected premiums to be earned, net of reinsurance, December 31, 2058	83
Future expected premiums to be earned, net of reinsurance, Total	$ 2,025,484