Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Number of shares issued pursuant to the terms of a deferred compensation arrangement.

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Unrecognized cost of unvested options awarded to employees as compensation.

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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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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Stock Option Plans - Narrative (Details) - USD ($)		3 Months Ended				6 Months Ended
Stock Option Plans - Narrative (Details) - USD ($)	Jun. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 28, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation (in shares)	111,350					3,271
Shares due to exercise of employee stock options and issuance of directors' deferred stock (in shares)		48,772	485	2,647	8,088
Stock option expense						$ 970,500
Future expense	$ 3,200,000	$ 3,200,000				$ 3,200,000
Closing share price (in usd per share)								$ 56.13
Granted (in shares)	1,320,614	1,320,614				1,320,614			1,114,169
Weighted average remaining contractual life of the Company's outstanding options						7 years 4 months 24 days
Weighted average remaining contractual life of the Company's exercisable options						6 years 4 months 24 days
2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)								210,875
2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)								227,500
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares due to exercise of employee stock options and issuance of directors' deferred stock (in shares)						6,565
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period							10 years
Officers \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period							4 years