XML 62 R51.htm IDEA: XBRL DOCUMENT v3.8.0.1

Stock-Based Compensation - Summary of Warrant Activity (Detail) - Outstanding Warrants	3 Months Ended
	Mar. 31, 2018 shares
Warrant [Line Items]
Warrants, Beginning Balance	17,721,088
Warrants exercised	(14,270)
Warrants, Ending Balance	17,706,818
Warrants, Vested and exercisable Ending Balance	16,966,218

X

- Definition

Vested and exercisable.

+ References

No definition available.

+ Details

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Namespace Prefix:	nk_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Stock issued during period shares warrants exercised.

+ References

No definition available.

+ Details

Name:	nk_StockIssuedDuringPeriodSharesWarrantsExercised
Namespace Prefix:	nk_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Warrant.

+ References

No definition available.

+ Details

Name:	nk_WarrantLineItems
Namespace Prefix:	nk_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

X

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_WarrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: