v3.8.0.1

Commitments and Contingencies - Additional Information (Details) $ in Thousands			1 Months Ended			3 Months Ended			12 Months Ended
	Aug. 04, 2014	Jul. 31, 2014 USD ($) ft²	Feb. 28, 2018 USD ($)	Aug. 31, 2017 USD ($) ft²	Mar. 31, 2016 ft²	Dec. 30, 2017 USD ($)	Apr. 01, 2017 USD ($)	Jun. 25, 2016 USD ($)	Dec. 30, 2017 USD ($) government_inquiry	Dec. 31, 2016 USD ($)	Dec. 26, 2015 USD ($)	Sep. 30, 2017 ft²	Apr. 14, 2016 ft²	Apr. 01, 2016 USD ($)
Capital Leased Assets [Line Items]
Facilities rent expense under operating leases									$ 4,000	$ 4,900	$ 5,200
Facilities rent expense under sub-leases									500	100
Lease term					5 years
Capital lease obligations						$ 42,900			42,900
Rent expense									2,900	$ 3,900	$ 4,200
Payments for operating lease						26,435			$ 26,435					$ 800
Loss contingency, damages sought, value							$ 1,500
Loss contingency, loss in period						$ 4,900
Number of government inquiries | government_inquiry									2
Prime Lease
Capital Leased Assets [Line Items]
Area of real estate property | ft²		108,743
Lease term	120 months
Tenant reimbursement allowance		$ 2,300
Payments for deposits									$ 2,800
Massachusetts
Capital Leased Assets [Line Items]
Area of real estate property | ft²													108,743
California
Capital Leased Assets [Line Items]
Lease term				2 years
Payments for operating lease				$ 700
Property Subject to Operating Lease | Massachusetts
Capital Leased Assets [Line Items]
Facilities rent expense under sub-leases								$ (200)
Area of real estate property | ft²				25,812								25,812	10,362
Property Subject to Operating Lease | California
Capital Leased Assets [Line Items]
Area of real estate property | ft²					2,100
Subsequent Event
Capital Leased Assets [Line Items]
Loss contingency, damages paid, value			$ 500

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Number of Government Inquiries

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Area of a real estate property.

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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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The charge for the use of long-lived depreciable capital leased assets for the period.

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Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of damages paid to the plaintiff in the legal matter.

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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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In accordance with the provisions of their lease agreement, this element represents allowable charges due a landlord from its tenant. In retail store and office building leases, for example, tenant reimbursements may cover items such as taxes, utilities, and common area expenses.

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