Fair Value Measurements - Information about Valuation Inputs for Fixed Income Securities Classified as Level 3 (Detail) - Successor [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities	$ 5,334,120	$ 5,150,018
Corporate Obligations [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon rate		0.345%
Fair Value Inputs Maturity		19 years 1 month 21 days
Yield		4.93%
Fair Value, Inputs, Level 3 [Member] | Corporate Obligations [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities	0	$ 3,808
Fair Value, Inputs, Level 3 [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities	488,884	194,393
Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities	$ 0	$ 0
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 9 months 22 days	15 years 10 months 4 days
Yield	9.14%	7.37%
Variable Interest Entity, Primary Beneficiary [Member] | European Transactions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon rate	1.38%	0.30%
Fair Value Inputs Maturity	16 years 4 months 39 days	21 years 2 months 30 days
Yield	6.08%	9.52%
Variable Interest Entity, Primary Beneficiary [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Obligations [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities	$ 2,588,556	$ 2,743,050