Borrowing Arrangements - Summary of Recognized Interest Expense on 2010 Notes and 2006 Notes (Detail) (Convertible Senior Subordinated Notes [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Convertible Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Contractual coupon interest	$ 5,719	$ 6,361
Amortization of discount	2,728	2,840
Amortization of deferred financing costs	644	720
Total interest expense	$ 9,091	$ 9,921