Tax Effects of Temporary Differences and Carry Forwards on Deferred Tax Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Net operating loss carry forwards	$ 89,491	$ 48,591
Capitalized start-up costs	9,406	9,931
Research and development credits	3,896	1,527
Stock compensation	9,390	5,522
Other	4,787	5,028
Total deferred tax assets	116,970	70,599
Valuation allowance	(114,337)	(69,571)
Deferred tax liability - fixed assets	(2,633)	(1,028)
Net deferred tax assets, after valuation allowance