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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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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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.

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Gross number of share options (or share units) granted during the period.

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Number of share instruments newly issued under a share-based compensation plan.

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Percentage of vesting of share-based compensation awards.

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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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Equity-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	May 02, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized	60,000,000		60,000,000			60,000,000
Expiration period			10 years
Compensation cost	$ 18,595	$ 10,878	$ 28,104	$ 21,467
Compensation cost not yet recognized	$ 347,900		$ 347,900
Compensation cost not yet recognized, period			2 years 9 months 18 days
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	166,000		340,000
Employee Stock Option [Member] \| Vesting over 2 Years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	34,000
Vesting period	2 years
Vesting percentage	50.00%
Employee Stock Option [Member] \| Vesting over 4 Years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	132,000
Vesting period	4 years
Vesting percentage	25.00%
Employee Performance Based Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	166,000
Employee Performance Based Stock Option [Member] \| Vesting over 2 Years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	34,000
Vesting period	2 years
Vesting percentage	50.00%
Employee Performance Based Stock Option [Member] \| Vesting over 4 Years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	132,000
Vesting period	4 years
Vesting percentage	25.00%
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, value per share			$ 3,022.99
Restricted Stock Units (RSUs) [Member] \| Vesting over 2 Years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years
Vesting percentage	50.00%
Performance Based Restricted Stock Unit [Member] \| Vesting over 2 Years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years
Vesting percentage	50.00%
Two Thousand Eighteen, Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized					275,000
Shares granted	144,000
Two Thousand Eighteen, Equity Plan [Member] \| Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	72,000
Two Thousand Eighteen, Equity Plan [Member] \| Employee Performance Based Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	72,000
Two Thousand Eighteen, Equity Plan [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized					40,000
Two Thousand Ten, Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	4,000
Two Thousand Ten, Equity Plan [Member] \| Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued	332,000
Shares granted	4,000
Two Thousand Ten, Equity Plan [Member] \| Employee Performance Based Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	0
Two Thousand Ten, Equity Plan [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued	16,000
Two Thousand Fourteen, Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	184,000
Two Thousand Fourteen, Equity Plan [Member] \| Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	90,000		8,000
Two Thousand Fourteen, Equity Plan [Member] \| Employee Stock Option [Member] \| Vesting over 4 Years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Vesting percentage			25.00%
Two Thousand Fourteen, Equity Plan [Member] \| Employee Stock Option [Member] \| Continued Employment and Return Of Capital Performance [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			50.00%
Two Thousand Fourteen, Equity Plan [Member] \| Employee Stock Option [Member] \| Continued Employment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			50.00%
Two Thousand Fourteen, Equity Plan [Member] \| Employee Performance Based Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	94,000