Derivative Instruments - Forward Contracts Outstanding, Estimated Fair Value, Change in Fair Value and Realized Gains of Derivative Instruments (Detail) In Thousands, unless otherwise specified		3 Months Ended					3 Months Ended			3 Months Ended			3 Months Ended			3 Months Ended			3 Months Ended
	Dec. 31, 2013 Fair Value [Member] USD ($)	Mar. 31, 2014 Forward Contracts [Member] Net Foreign Exchange Gains (Losses) [Member] USD ($)	Mar. 31, 2013 Forward Contracts [Member] Net Foreign Exchange Gains (Losses) [Member] USD ($)	Mar. 31, 2014 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] USD ($)	Mar. 31, 2013 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] USD ($)	Mar. 31, 2014 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] AUD	Mar. 31, 2014 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] USD ($)	Mar. 31, 2013 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] USD ($)	Mar. 31, 2014 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] AUD	Mar. 31, 2014 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] USD ($)	Mar. 31, 2013 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] USD ($)	Mar. 31, 2014 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] AUD	Mar. 31, 2014 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] USD ($)	Mar. 31, 2013 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] USD ($)	Mar. 31, 2014 Forward Contracts [Member] Foreign Exchange Forward Contract [Member] Net Foreign Exchange Gains (Losses) [Member] GBP (£)	Mar. 31, 2014 Forward Contracts [Member] Fair Value [Member] Foreign Exchange Forward Contract [Member] USD ($)	Mar. 31, 2014 Forward Contracts [Member] Fair Value [Member] Foreign Exchange Forward Contract [Member] AUD	Dec. 31, 2013 Forward Contracts [Member] Fair Value [Member] Foreign Exchange Forward Contract [Member] USD ($)	Mar. 31, 2014 Forward Contracts [Member] Fair Value [Member] Foreign Exchange Forward Contract [Member] USD ($)	Mar. 31, 2014 Forward Contracts [Member] Fair Value [Member] Foreign Exchange Forward Contract [Member] AUD	Dec. 31, 2013 Forward Contracts [Member] Fair Value [Member] Foreign Exchange Forward Contract [Member] USD ($)
Derivative [Line Items]
Contract Date				Nov. 26, 2013			Jul. 01, 2013			Feb. 08, 2012			Mar. 06, 2012			Nov. 26, 2013	Nov. 26, 2013		Jul. 01, 2013	Jul. 01, 2013
Contract Amount and Settlement Amount				$ 41,036		45,000	$ 40,887		45,000	$ 36,099		35,000	$ 26,611		£ 17,000	$ 41,036	45,000		$ 40,887	45,000
Fair Value	149																	779			(630)
Settlement Date				Jan. 03, 2014			Jan. 03, 2014			May 10, 2013			Mar. 06, 2013			Jan. 03, 2014	Jan. 03, 2014		Jan. 03, 2014	Jan. 03, 2014
Net Foreign Exchange Gains (Losses)			$ 873	$ (130)			$ 130				$ (150)			$ 1,023