Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Apr. 30, 2014
Significant Accounting Policies [Line Items]
Long-term Debt, Fair Value	$ 764,000,000
Long-term Debt	$ 766,796,000		$ 820,000,000
Estimated useful life of amortizable intangible assets	8 years 6 months	9 years 4 months
Minimum
Significant Accounting Policies [Line Items]
Estimated useful life of amortizable intangible assets	3 years
Maximum
Significant Accounting Policies [Line Items]
Estimated useful life of amortizable intangible assets	15 years