Allowed annual percentage increase in shares authorized as percentage of outstanding shares of common stock.

No definition available.

Name:	dtil_AllowedAnnualPercentageIncreaseInSharesAuthorizedAsPercentageOfOutstandingSharesOfCommonStock
Namespace Prefix:	dtil_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum shares allowed to be issued under ESPP.

+ References

No definition available.

+ Details

Name:	dtil_MaximumSharesAllowedToBeIssuedUnderESPP
Namespace Prefix:	dtil_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Offering period commenced date.

+ References

No definition available.

+ Details

Name:	dtil_OfferingPeriodCommencedDate
Namespace Prefix:	dtil_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Offering period end date.

+ References

No definition available.

+ Details

Name:	dtil_OfferingPeriodEndDate
Namespace Prefix:	dtil_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation arrangement by share based payment award purchase price of common stock through payroll deductions percentage.

+ References

No definition available.

+ Details

Name:	dtil_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePriceOfCommonStockThroughPayrollDeductionsPercentage
Namespace Prefix:	dtil_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ 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))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockSharesIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ 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 (i)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ 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)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- 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

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ 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
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_PlanNameAxis=dtil_TwoThousandSixStockIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=dtil_TwoThousandFifteenStockIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=dtil_TwoThousandNineteenIncentiveAwardPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=dtil_TwoThousandNineteenEmployeeStockPurchasePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Share-Based Compensation - Additional Information (Details) - USD ($) $ in Millions			3 Months Ended
	Mar. 31, 2020	Mar. 12, 2019	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Mar. 31, 2019	May 31, 2018	Dec. 31, 2016	Apr. 30, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding	8,986,436		8,986,436		8,919,116
Stock options outstanding			414,856
Common stock, shares issued	52,253,327		52,253,327		51,965,708
Unrecognized compensation cost	$ 28.9		$ 28.9
Weighted-average period for recognition of compensation cost			2 years 9 months 18 days
Intrinsic value of Stock options exercised	$ 2.1		$ 2.1			$ 1.9
2006 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining shares available to be granted								0
Options outstanding	1,380,203		1,380,203
2015 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding	5,152,693		5,152,693
Common stock reserved for issuance							8,211,980		5,270,095
2019 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance		4,750,000		2,046,209
Allowed annual percentage increase in shares authorized as percentage of outstanding shares of common stock		4.00%
Stock options outstanding	2,453,540
2019 ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance		525,000		511,552
Allowed annual percentage increase in shares authorized as percentage of outstanding shares of common stock		1.00%
Maximum shares allowed to be issued under ESPP		5,250,000
Purchase of common stock through payroll deductions expressed in percentage of fair market value		85.00%
Offering period commenced date	Mar. 01, 2020	Oct. 21, 2019
Offering period end date	Aug. 31, 2020	Feb. 29, 2020
Common stock, shares issued		42,620