Fair Value Measurements - Information about Valuation Inputs for Fixed Income Securities Classified as Level 3 (Detail) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities	$ 6,151,939	$ 5,334,120
Asset-backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon rate	5.96%
Fair Value Inputs Maturity	18 years 3 months 20 days
Yield	12.25%
Variable Interest Entity, Primary Beneficiary [Member] | United States Transactions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon rate	5.88%	5.88%
Fair Value Inputs Maturity	21 years 6 months 23 days	21 years 9 months 23 days
Yield	7.50%	9.14%
Fair Value, Inputs, Level 3 [Member] | Corporate Obligations [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities	$ 0	$ 0
Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities	71,786	0
Fair Value, Inputs, Level 3 [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Corporate Obligations [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities	$ 2,622,724	$ 2,588,556