Performance-based stock awards outstanding.

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- Definition

Share based compensation arrangement by share based payment award employee stock purchase plan offering term.

+ References

No definition available.

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- Definition

Share based compensation arrangement by share based payment award number of purchase period.

+ References

No definition available.

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- Definition

Share based compensation arrangement by share based payment award term.

+ References

No definition available.

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- Definition

Aggregate number of common shares reserved for future issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29)
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- Definition

Aggregate cash paid by the entity during the period to settle equity instruments granted under equity-based payment arrangements.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- 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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Paragraph 2
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- Definition

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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 2
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- Definition

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.

+ References

No definition available.

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- Definition

Number of additional shares authorized for issuance under an established share-based compensation plan.

+ References

No definition available.

+ Details

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
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- Definition

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.

+ References

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- Definition

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

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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- Definition

Description of significant modifications (such as a change in expiration dating, vesting rights, or exercise prices) to an equity-based compensation plan, including the terms of the modifications.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Purchase price of common stock expressed as a percentage of its fair value.

+ References

No definition available.

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Stock-Based Compensation - Additional Information (Detail) $ in Millions			9 Months Ended
	Jun. 07, 2017 shares	Jun. 10, 2015 shares	Sep. 30, 2018 USD ($) Period shares	Dec. 31, 2017 shares	Aug. 31, 2016 shares	Jun. 12, 2013 shares
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, option to be granted at percentage of fair value of common stock			85.00%
Employee Stock Purchase Plan, offering period			12 months
Number of purchase periods within each offering period \| Period			2
Aggregate number of shares of common stock reserved for future issuance			800,000
2008 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, option to be granted at percentage of fair value of common stock			100.00%
Aggregate number of shares of common stock reserved for future issuance			23,200,000
Employee Stock Purchase Plan, authorized shares for issuance						19,500,000
Increase in shares of common stock authorized for issuance	6,000,000	5,000,000
Stock-based compensation, award term			10 years
Performance-based stock awards, outstanding			25,000
Outstanding options and other stock based awards			17,622,000	17,138,000
Number of shares available for future issuance			3,600,000
2008 Equity Incentive Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, vesting period			4 years
2008 Equity Incentive Plan \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, vesting period			3 years
Number of unvested Restricted Stock Units			1,978,000	1,256,000
2008 Equity Incentive Plan \| Performance-based Stock or Cash Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan, authorized shares for issuance			500,000
Stock option plan granted on cash award \| $			$ 1.0
Cerus Corporation Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares of common stock reserved for future issuance					1,250,000
Share based compensation modification terms			Effective June 7, 2017, the Company no longer issues shares from the Inducement Plan.