Convertible subordinated notes maturity date.

No definition available.

Name:	nktr_ConvertibleSubordinatedNotesMaturityDate
Namespace Prefix:	nktr_
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Period Type:	duration

- Definition

Convertible subordinated notes repaid.

+ References

No definition available.

+ Details

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Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument Exchanged Amount

+ References

No definition available.

+ Details

Name:	nktr_DebtInstrumentExchangedAmount
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Minimum Required Cash Balance

+ References

No definition available.

+ Details

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Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Redemption Price As Percentage Of Principal Amount In Case Of Change Of Control

+ References

No definition available.

+ Details

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Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Redemption Price As Percentage Of Principal Amount In Case Of Sale Of Assets

+ References

No definition available.

+ Details

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Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

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

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

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

+ Details

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees).

+ References

No definition available.

+ Details

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

- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.1)

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

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16(a))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=nktr_JulyFirstTwoThousandFifteenThroughJuneThirtyTwoThousandSeventeenMember
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- Details

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- Details

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- Details

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Senior Secured Notes - Additional Information (Detail) (USD $)	12 Months Ended	1 Months Ended	0 Months Ended
	Dec. 31, 2014	Jul. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Jul. 11, 2012
Line of Credit Facility [Line Items]
Senior secured notes, issued	$ 125,000,000us-gaap_SeniorLongTermNotes		$ 125,000,000us-gaap_SeniorLongTermNotes	$ 125,000,000us-gaap_SeniorLongTermNotes
Convertible subordinated notes remaining					172,400,000nktr_ConvertibleSubordinatedNotesRepaid
Maturity date of convertible subordinated notes	Sep. 28, 2012
Restricted cash	25,000,000		25,000,000	25,000,000	25,000,000
Percentage of repurchase of notes on principal amount of notes	101.00%
Percentage of repurchase of notes on principal amount of notes	100.00%
Convertible Subordinated Notes [Member]
Line of Credit Facility [Line Items]
Retirement of convertible subordinated notes		42,500,000
12% Senior Secured Notes Due July 2017 [Member]
Line of Credit Facility [Line Items]
Senior secured notes, issued					125,000,000
Maturity date of senior secured notes	Jul. 15, 2017	Jul. 15, 2017
Interest rate	12.00%		12.00%		12.00%
Issuance costs		4,500,000
July 1, 2015 through June 30, 2017 [Member]
Line of Credit Facility [Line Items]
Minimum Cash Requirement (Jul 1, 2015 through June 30, 2017)	25,000,000		25,000,000
12% Senior Secured Notes Due July 2017 [Member]
Line of Credit Facility [Line Items]
Maturity date of senior secured notes			Jul. 15, 2017
Interest rate	12.00%		12.00%
Senior Secured Notes carrying amount	$ 125,000,000		$ 125,000,000