Income Taxes - Deferred Income Taxes Differences Between Carrying Amounts of Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 27, 2014	Dec. 28, 2013
Deferred tax assets:
Net operating losses	$ 107,601	$ 123,908
Research credits	37,435	33,647
Nondeductible accruals	31,151	26,365
Inventory valuation	19,625	13,540
Property, plant and equipment	1,387	1,453
Intangible assets	2,119	3,446
Stock-based compensation	12,830	15,454
Total deferred tax assets	212,148	217,813
Valuation allowance	(199,698)	(202,747)
Net deferred tax assets	12,450	15,066
Deferred tax liabilities:
Depreciation	(203)	(161)
Convertible senior notes	(12,167)	(14,941)
Total deferred tax liabilities	(12,370)	(15,102)
Net deferred tax assets (liabilities)	$ 80	$ (36)