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Stock Option Plans - Narrative (Details) - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 28, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option expiration period	10 years
Option vesting period	4 years
Closing share price (in usd per share)		$ 56.00
Granted (in shares)	1,124,169		913,320
Weighted average remaining contractual life of the Company's outstanding options	7 years 5 months 6 days
Weighted average remaining contractual life of the Company's exercisable options	6 years 4 months 23 days
2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	213,375
2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	230,000

X

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of options outstanding, including both vested and non-vested options.

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Price of a single share of a number of saleable stocks of a company.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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