Convertible Notes (Interest Expense for the Series 2012 Notes) (Detail) (Series 2012 Notes [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Series 2012 Notes [Member]
Debt Instrument [Line Items]
Contractual coupon interest	$ 347	$ 1,287	$ 1,108	$ 2,573
Amortization of debt issuance costs	62	287	932	571
Amortization of debt discount	399	1,513	1,379	3,000
Total	$ 808	$ 3,087	$ 3,419	$ 6,144