Investments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended		2 Months Ended	3 Months Ended	6 Months Ended		1 Months Ended	4 Months Ended					2 Months Ended	3 Months Ended	6 Months Ended	1 Months Ended	4 Months Ended	0 Months Ended	4 Months Ended	6 Months Ended
	Mar. 31, 2014	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013 Successor Ambac [Member]	Jun. 30, 2014 Successor Ambac [Member]	Jun. 30, 2014 Successor Ambac [Member]	Dec. 31, 2013 Successor Ambac [Member]	Apr. 30, 2013 Predecessor Ambac [Member]	Apr. 30, 2013 Predecessor Ambac [Member]	Jun. 30, 2014 Below Investment Grade Securities and Non-Rated Securities [Member] Successor Ambac [Member]	Dec. 31, 2013 Below Investment Grade Securities and Non-Rated Securities [Member] Successor Ambac [Member]	Jun. 30, 2014 Residential Mortgage-Backed Securities [Member] Successor Ambac [Member]	Jun. 30, 2014 Ambac Wrapped Securities [Member] Successor Ambac [Member]	Jun. 30, 2013 Gains (losses) on securities held as of reporting date [Member] Successor Ambac [Member]	Jun. 30, 2014 Gains (losses) on securities held as of reporting date [Member] Successor Ambac [Member]	Jun. 30, 2014 Gains (losses) on securities held as of reporting date [Member] Successor Ambac [Member]	Apr. 30, 2013 Gains (losses) on securities held as of reporting date [Member] Predecessor Ambac [Member]	Apr. 30, 2013 Gains (losses) on securities held as of reporting date [Member] Predecessor Ambac [Member]	Dec. 06, 2013 National Century Financial Enterprises, Inc. [Member]	Apr. 30, 2013 National Century Financial Enterprises, Inc. [Member]	Jun. 30, 2014 National Century Financial Enterprises, Inc. [Member]	Jun. 30, 2013 National Century Financial Enterprises, Inc. [Member]	Jun. 30, 2014 Fixed Income Securities [Member] Successor Ambac [Member]	Dec. 31, 2013 Fixed Income Securities [Member] Successor Ambac [Member]	Jun. 30, 2014 Fixed Income Securities [Member] Residential Mortgage-Backed Securities [Member] Successor Ambac [Member]	Dec. 31, 2013 Fixed Income Securities [Member] Residential Mortgage-Backed Securities [Member] Successor Ambac [Member]	Jun. 30, 2014 Fixed Income Securities [Member] Asset-backed Securities [Member] Successor Ambac [Member]	Dec. 31, 2013 Fixed Income Securities [Member] Asset-backed Securities [Member] Successor Ambac [Member]
Investment [Line Items]
Fair value of below investment grade securities and non-rated securities										$ 279,145	$ 826,969
Gross unrealized loss										9,109	36,946
Payment of permitted policy claim (percent)		25.00%
Future payment of permitted policy claim (percent)		45.00%
Unrealized losses on securities					11,511	11,511	116,634																11,510	116,634	7,186	18,105	32	36,598
Investment realized losses				18,472		19,356			53,305
Cash recoveries	7,760																		1,441	39,978	0	39,978
Securities fair value		6,800	6,799
Fair value of securities held by bankruptcy remote trust		278,317	240,150
Other investments				(3,015)	3,211	5,205		912	369					(3,015)	3,211	5,636	912	369
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments					$ 30,342	$ 30,342	$ 116,634					$ 7,376	$ 5,521