Borrowings - Aggregate Amounts of Long-Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014
Debt Disclosure [Abstract]
2015	$ 404,598	[1]
2016	0
2017	0
2018	200,000
2019 and thereafter	$ 500,000

[1] The Convertible Notes are included in amounts that will mature in 2015 because, at December 31, 2014, they were convertible in accordance with their terms, which are described in more detail above in this section under “Convertible Notes.”