Share based compensation arrangement by share based payment award exercise period after employment termination.

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- Definition

Share based compensation arrangement by share based payment award increase percentage of common stock outstanding.

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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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- Definition

Share based compensation arrangement by share based payment award percentage maximum incentive vesting.

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- Definition

Share based compensation by share based payment award percentage of fair market value of share of common stock on purchase date.

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- Definition

Share based compensation by share based payment award percentage of fair market value of a share of common stock on offering date.

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Aggregate number of common shares reserved for future issuance.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Amount of noncash expense for share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Description of terms of share-based payment arrangement. Includes, but is not limited to, type of award or grantee and reason for issuance.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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The number of grants made 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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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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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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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Number of shares authorized for issuance under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Per share or per unit amount of equity securities issued.

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Number of new stock issued during the period.

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Share-Based Compensation - Additional Information (Detail) - USD ($)			3 Months Ended
	Nov. 09, 2018	Apr. 24, 2018	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, share Reserve				4,335,286
Shares reserved for issuance increase percentage		3.00%
Share-based compensation expense			$ 12,500,000	$ 6,000,000.0
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense related to unvested stock options not yet recognized			0
Term Based Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense related to unvested stock options not yet recognized			$ 75,900,000
Share-based compensation expense related to unvested awards expected to be recognized over a weighted average period			1 year 10 months 24 days
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense related to unvested awards expected to be recognized over a weighted average period			1 year 8 months 12 days
Stock options, vested			138,687
Unvested restricted stock units outstanding			472,251
Vested restricted stock units outstanding			395,338
Share-based compensation expense related to unvested restricted stock units not yet recognized			$ 16,500,000
Restricted Stock Units (RSUs) [Member] \| Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period			1 year
Restricted Stock Units (RSUs) [Member] \| Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period			3 years
Restricted Stock Units (RSUs) [Member] \| Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period			4 years
HCM Stock Incentive Plan 2007 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares outstanding			2,500
HCM Stock Incentive Plan 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares outstanding			4,657,548
Share based compensation arrangement by share based payment award exercise period after employment termination			90 days
Stock option awards, contractual term			10 years
HCM Stock Incentive Plan 2013 [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period			4 years
HCM Stock Incentive Plan 2013 [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period			5 years
HCM Equity Incentive Plan 2018 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares outstanding			9,164,882
Restricted stock vesting period		4 years
Share based compensation arrangement by share based payment award exercise period after employment termination		90 days
Stock option awards, contractual term		10 years
Number of shares authorized		13,500,000
Shares available for future grants of equity awards			12,866,597
HCM Equity Incentive Plan 2018 [Member] \| Performance Stock Units ("PSUs") [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSUs, granted			145,017
PSUs, Weighted average grant date fair value per share			$ 70.73
PSUs, forfeited and cancelled			111
HCM Global Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option awards, contractual term	10 years
Description for purchase price of fair market value of common stock			The purchase price is the lower of (i) 85% of the fair market value of a share of common stock on the offering date (the first trading day of the offering period commencing on January 1 and concluding on December 31) or (ii) 85% of the fair market value of a share of common stock on the purchase date.
Percentage of fair market value of a share of common stock on offering date	85.00%
Percentage of fair market value of share of common stock on purchase date	85.00%
HCM Global Employee Stock Purchase Plan [Member] \| Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock, shares			49,802
Share purchase price			$ 42.56
HCM Global Employee Stock Purchase Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	2,500,000
2020 Management Incentive Plan [Member] \| Performance Stock Units ("PSUs") [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum incentive vesting of PSUs			125.00%
Share-based compensation expense related to unvested PSUs not yet recognized			$ 10,300,000