Special Purpose Entities, Including Variable Interest Entities - Summary of Fair Value of Fixed Income Securities, by Asset-Type, Held by Consolidated Variable Interest Entities (Detail) - Successor [Member] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investments:
Fixed income securities	$ 6,049,908	$ 5,334,120
Variable Interest Entities [Member]
Investments:
Fixed income securities	2,622,566	2,588,556
Corporate Obligations [Member]
Investments:
Fixed income securities	$ 2,622,566	$ 2,588,556