Income Taxes (Tables)

12 Months Ended

Dec. 27, 2014

Income Tax Disclosure [Abstract]

Geographic Breakdown of Provision for (Benefit from) Income Taxes

The following is a geographic breakdown of the provision for income taxes (in thousands):

	Years Ended
	December 27, 2014			December 28, 2013			December 29, 2012
Current:
Federal	$	—		$	—		$	(133	)
State	446			(135		)	22
Foreign	2,423			1,719			2,169
Total current	$	2,869		$	1,584		$	2,058
Deferred:
Federal	$	—		$	—		$	—
State	—			—			—
Foreign	(116		)	70			132
Total deferred	$	(116	)	$	70		$	132
Total provision	$	2,753		$	1,654		$	2,190

Provisions for Income Taxes Computed by Applying Statutory Federal Income Tax Rates

The provisions for income taxes differ from the amount computed by applying the statutory federal income tax rates as follows:

	Years Ended
	December 27, 2014		December 28, 2013		December 29, 2012
Expected tax at federal statutory rate	35.0	%	35.0	%	35.0	%
State taxes, net of federal benefit	1.8	%	0.3	%	—	%
Research credits	(11.4	)%	4.9	%	—	%
Stock-based compensation	14.7	%	(12.2	)%	(3.9	)%
Change in valuation allowance	(25.3	)%	(34.2	)%	(33.5	)%
Other	2.0	%	0.8	%	(0.2	)%
Effective tax rate	16.8	%	(5.4	)%	(2.6	)%

Deferred Income Taxes Differences between Carrying Amounts of Assets and Liabilities

Significant components of the Company’s deferred tax assets are as follows (in thousands):

	Years Ended
	December 27, 2014			December 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	)

Aggregate Changes in Balance of Gross Unrecognized Tax Benefits

The aggregate changes in the balance of gross unrecognized tax benefits were as follows (in thousands):

	December 27, 2014			December 28, 2013			December 29, 2012
Beginning balance	$	15,148		$	13,902		$	13,066
Tax position related to current year
Additions	1,990			1,676			1,437
Tax positions related to prior years
Additions	140			32			75
Reductions	(76		)	(132		)	(580		)
Lapses of statute of limitations	(224		)	(330		)	(96		)
Ending balance	$	16,978		$	15,148		$	13,902