Investments - Summary of Net Investment Income (Detail) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Investment [Line Items]
Fixed income securities	$ 66,104	$ 64,627	$ 125,527	$ 130,213
Short-term investments	374	60	930	101
Loans	70	93	176	225
Investment expense	(2,180)	(2,502)	(4,283)	(4,929)
Securities available-for-sale and short-term	64,368	62,278	122,350	125,610
Other investments	6,390	2,475	9,229	12,126
Total net investment income	70,758	64,753	131,579	137,736
Gains (losses) on securities held as of reporting date [Member]
Investment [Line Items]
Net Realized and Unrealized Gain (Loss) on Trading Securities	5,240	1,419	6,948	10,042
Trading Securities, Realized Gain (Loss)	1,498	3,069	1,531	5,453
Other investments	$ 3,742	$ (1,650)	$ 5,417	$ 4,589