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Sharebased compensation arrangement by sharebased payment award share reserve.

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Amount of cost not yet recognized for nonvested award under 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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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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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 equity instruments other than options outstanding, including both vested and non-vested instruments.

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

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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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

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An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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Percentage of vesting of award under share-based payment arrangement.

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Amount of cost expensed and capitalized for award under share-based payment arrangement.

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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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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Number of shares of stock issued during the period pursuant to acquisitions.

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Share-Based and Long-Term Incentive Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions						12 Months Ended
	Mar. 15, 2021	Mar. 14, 2021	Feb. 17, 2021	Feb. 19, 2020	Feb. 20, 2019	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase to number of ordinary shares authorized						4,800,000
Common stock shares reserved for future issuance						2,046,575
Stock option granted						0	0
Share-based payment award options, outstanding						4,830,232	6,209,583
Stock options contractual term						10 years
Total intrinsic value of options exercised						$ 102.9	$ 160.1	$ 79.8
Total fair value of stock options vested						14.5	51.4	3.5
Total compensation cost						17.9
Tax benefit (detriment) recognized from stock-based compensation expense						62.6	86.9
Pre-tax unrecognized compensation expense for all unvested share-based awards						247.2
Senior Executives [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental expense						$ 6.4
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted shares granted to purchase common stock						2,034,407
Weighted Average Grant Date Fair Value						$ 97.91
Total fair value of restricted stock units vested						$ 112.2	$ 79.6	$ 54.6
Restricted Stock Units [Member] \| Employees and Nonexecutive Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted shares granted to purchase common stock						2,034,407	2,211,264	2,781,080
Weighted Average Grant Date Fair Value						$ 97.91	$ 78.35	$ 39.01
Performance Stock Unit Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted shares granted to purchase common stock						309,470
Weighted Average Grant Date Fair Value						$ 138.41
Percentage of outstanding PSU award vesting amount range						150.00%
Performance Stock Unit Awards [Member] \| TEPEZZA [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
PSUs outstanding						68,459
Performance Stock Unit Awards [Member] \| Relative TSR PSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of outstanding PSU award vesting amount range						50.00%	50.00%	30.00%
Vesting period							3 years	3 years
Performance Stock Unit Awards [Member] \| Strategic PSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of outstanding PSU award vesting amount range						30.00%
Performance Stock Unit Awards [Member] \| Financial PSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of outstanding PSU award vesting amount range						20.00%
Performance Stock Unit Awards [Member] \| Tech Ops PSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of outstanding PSU award vesting amount range							25.00%
Vesting period							3 years
Performance Stock Unit Awards [Member] \| Net Sales PSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of outstanding PSU award vesting amount range								70.00%
Vesting period							2 years	1 year
Performance Stock Unit Awards [Member] \| R&D PSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of outstanding PSU award vesting amount range							25.00%
Vesting period							2 years
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average fair value of options granted to purchase common stock		$ 87.84
Restricted stock units, vesting period						3 years
Maximum [Member] \| Performance Stock Unit Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of outstanding PSU award vesting amount range						200.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average fair value of options granted to purchase common stock		$ 26.05
Restricted stock units, vesting period						1 year
Minimum [Member] \| Performance Stock Unit Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of outstanding PSU award vesting amount range						0.00%
Viela Bio [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award options, outstanding						1,300,000
2014 ESPP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase to number of ordinary shares authorized				2,500,000
2020 ESPP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Ordinary shares, initial share reserve						2,500,000
2014 EIP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase to number of ordinary shares authorized				6,900,000
2014 Non-Employee Equity Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase to number of ordinary shares authorized					750,000
2020 EIP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase to number of ordinary shares authorized			7,000,000
Common stock shares available for grant						18,974,953
2018 EIP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares available for grant						1,650,775
2018 EIP [Member] \| Viela [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase of common stock shares	1,318,053
Common stock shares available for grant	2,359,550
2018 EIP [Member] \| Viela [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares authorized	3,677,603
2014 Non-Employee Equity Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares available for grant						483,069