Borrowing Arrangements - Summary of Carrying Amount of Debt and Equity Components (Detail) (2010 Convertible Senior Subordinated Notes [Member], USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
2010 Convertible Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Principal amount of notes	$ 97,650,000	$ 130,000,000
Unamortized discount	(2,426,000)	(5,494,000)
Net carrying amount	95,224,000	124,506,000
Additional paid-in-capital, net of tax	$ 8,555,000	$ 8,555,000