Fair Value Measurements - Information about Valuation Inputs for Fixed Income Securities Classified as Level 3 (Detail)	1 Months Ended	12 Months Ended
	Apr. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2014
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon rate	5.01%
Successor [Member] | United States Transactions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon rate		5.88%	6.11%
Fair Value Inputs Maturity		15 years 10 months 4 days	6 years 9 months 28 days
Yield			11.95%	7.37%
Successor [Member] | European Transactions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon rate		0.30%	0.72%
Fair Value Inputs Maturity		21 years 2 months 30 days	17 years 9 months 40 days
Yield		9.52%	8.02%
Successor [Member] | Corporate Obligations [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon rate		0.345%	0.345%
Fair Value Inputs Maturity		19 years 1 month 21 days	20 years 1 month 19 days
Yield		4.93%	6.30%
Successor [Member] | U.S. Agency Obligations [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon rate			6.98%
Fair Value Inputs Maturity			1 year 4 months 13 days
Yield			0.39%
Successor [Member] | Asset-backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon rate			0.64%
Fair Value Inputs Maturity			7 years 1 month 24 days
Yield			5.17%