Reservation payment that will be credited against future purchases of batches under the agreement.

No definition available.

Name:	ptla_CommercialSupplyAgreementReservationPayment
Namespace Prefix:	ptla_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Upfront payment that will be credited against future purchases of batches under the agreement.

+ References

No definition available.

+ Details

Name:	ptla_CommercialSupplyAgreementUpfrontPayment
Namespace Prefix:	ptla_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Payments related to commercial supply agreement.

+ References

No definition available.

+ Details

Name:	ptla_PaymentsRelatedToCommercialSupplyAgreement
Namespace Prefix:	ptla_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The minimum amount the entity agreed to spend under the long-term purchase commitment.

+ References

No definition available.

+ Details

Name:	us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Definition

The amount of the loss on termination of a contract for default.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 912

-SubTopic 20

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6539154&loc=d3e52595-109384

+ Details

Name:	us-gaap_LossOnContractTerminationForDefault
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Commercial Supply Agreements - Additional Information (Detail) (CMC ICOS Biologics Inc, USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Jul. 31, 2014	Dec. 31, 2014	Nov. 01, 2014
Long Term Purchase Commitment [Line Items]
Commercial supply agreement upfront payment	$ 10.0	$ 14.6
Commercial supply (manufacturing services) agreement reservation payment			4.6
Commercial agreement fixed commitment amount	293.9
Payments related to commercial supply agreement		2.6
Minimum
Long Term Purchase Commitment [Line Items]
Termination fees payment under obligation	16.0
Maximum
Long Term Purchase Commitment [Line Items]
Termination fees payment under obligation	$ 30.0