Income Taxes - Reconciliation Between Provision for Income Taxes and Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Computed "expected" tax benefit	$ (10,621)	$ (7,712)	$ (2,606)
State income taxes, net of federal benefit	(1,947)	451	(545)
Tax effect of:
Change in valuation allowance	13,074	(37,179)	2,185
Expiration of prior year credits and net operating losses	(237)	45,382	1,880
Research and development and other tax credits carryovers	(672)	(1,097)	(1,468)
Stock compensation	337	358	297
Other	66	(203)	257
Provision for income taxes