Leases - Maturities of lease liabilities under non-cancellable operating leases (Details) $ in Thousands	3 Months Ended
Mar. 30, 2019 USD ($)
Operating lease commitments
2019 (excluding the three months ended March 30, 2019)	$ 10,988
2020	14,083
2021	14,028
2022	14,070
2023	14,178
Thereafter	55,320
Total lease payments	122,667
Less: imputed interest	(18,170)
Total	104,497
Additional operating leases that have not yet commenced	$ 52,700
Minimum
Operating lease commitments
Commencement of operating lease term	5 years
Maximum
Operating lease commitments
Commencement of operating lease term	11 years

Lessee operating lease, lease not yet commenced amount.

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Term of lessee's operating lease that has not yet commenced, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

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- Definition

Amount of lessee's undiscounted obligation for lease payments for operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payments for operating lease, due after fifth fiscal year following latest fiscal year.

+ References

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- Definition

Amount of lessee's undiscounted obligation for lease payments for operating lease, due in fifth fiscal year following latest fiscal year.

+ References

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payments for operating lease, due in fourth fiscal year following latest fiscal year.

+ References

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payments for operating lease, due in third fiscal year following latest fiscal year.

+ References

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payments for operating lease, due in second fiscal year following latest fiscal year.

+ References

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payments for operating lease having an initial or remaining lease term in excess of one year due in remainder of fiscal year following latest fiscal year.

+ References

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating lease.

+ References

+ Details

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- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

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