Debt - Interest Expense (Detail) (Convertible Notes [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013
Convertible Notes [Member]
Debt Instrument [Line Items]
Interest expense - stated coupon rate	$ 948	$ 1,806
Interest expense - amortization of debt discount	710	1,317
Total interest expense - convertible notes	$ 1,658	$ 3,123