Business Acquisition Acquired Entity Purchase Price

No definition available.

Name:	sppi_BusinessAcquisitionAcquiredEntityPurchasePrice
Namespace Prefix:	sppi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Acquisition Contingent Consideration Potential Cash Payments

+ References

No definition available.

+ Details

Name:	sppi_BusinessAcquisitionContingentConsiderationPotentialCashPayments
Namespace Prefix:	sppi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Acquisition Cost Of Acquired Entity Contingent Value Right

+ References

No definition available.

+ Details

Name:	sppi_BusinessAcquisitionCostOfAcquiredEntityContingentValueRight
Namespace Prefix:	sppi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Acquisition Equity Interests Issued or Issuable Per Share

+ References

No definition available.

+ Details

Name:	sppi_BusinessAcquisitionEquityInterestsIssuedOrIssuablePerShare
Namespace Prefix:	sppi_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Contingent Value Rights Expected Rate

+ References

No definition available.

+ Details

Name:	sppi_ContingentValueRightsExpectedRate
Namespace Prefix:	sppi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Estimated Cash Flows In Years

+ References

No definition available.

+ Details

Name:	sppi_EstimatedCashFlowsInYears
Namespace Prefix:	sppi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Intangible assets discount rate.

+ References

No definition available.

+ Details

Name:	sppi_IntangibleAssetsDiscountRate
Namespace Prefix:	sppi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Milestone Payments

+ References

No definition available.

+ Details

Name:	sppi_MilestonePayments
Namespace Prefix:	sppi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage Of Royalty Paid On Net Sales

+ References

No definition available.

+ Details

Name:	sppi_PercentageOfRoyaltyPaidOnNetSales
Namespace Prefix:	sppi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

+ Details

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

- Definition

Number of shares of equity interests issued or issuable to acquire entity.

+ References

+ Details

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

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

- Definition

Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e7008-128479

+ Details

Name:	us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 35
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6911338&loc=d3e6819-128478

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

+ Details

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

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

+ Details

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

- Definition

Cash received from licensees for license fees during the current period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3536-108585

+ Details

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

- Definition

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

+ Details

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

- Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_InProcessResearchAndDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=sppi_MilestonePaymentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=sppi_MilestonePaymentOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=sppi_MilestonePaymentTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=sppi_MilestonePaymentThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=sppi_MilestonePaymentFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=sppi_MenadioneTopicalLotionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=sppi_TalonTherapeuticsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=sppi_LigandPharmaceuticalsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=sppi_AllosTherapeuticsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=sppi_LigandPharmaceuticalsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Business Combinations and Contingent Consideration - Additional Information (Details) - USD ($)		1 Months Ended			3 Months Ended									12 Months Ended
	Jul. 17, 2013	Apr. 30, 2016	Mar. 31, 2016	Mar. 31, 2013	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2012
Business Acquisition [Line Items]
Revenue milestone threshold					$ 29,402,000	$ 25,268,000	$ 24,168,000	$ 30,495,000	$ 28,570,000	$ 36,395,000	$ 34,301,000	$ 29,101,000		$ 109,333,000	$ 128,367,000	$ 146,444,000
License fees received				$ 3,000,000
Royalties payout percentage on our future net sales of licensed products					20.00%									20.00%
Acquisition-related contingent obligations														$ 0	$ 0	$ (1,300,000)
IPR&D [Member]
Business Acquisition [Line Items]
Estimated cash flow period														10 years
Estimated cash flow discount rate					25.00%									25.00%
Milestone Payments [Member]
Business Acquisition [Line Items]
Milestone net sales achievement	$ 5,000,000.0													$ 60,000,000
Revenue milestone threshold	30,000,000
Ligand Contingent Consideration		$ 7,700,000	$ 6,000,000										$ 6,000,000
Milestone Payment One [Member]
Business Acquisition [Line Items]
Milestone net sales achievement	10,000,000.0
Revenue milestone threshold	60,000,000
Milestone Payment Two [Member]
Business Acquisition [Line Items]
Milestone net sales achievement	25,000,000.0
Revenue milestone threshold	100,000,000
Milestone Payment Three [Member]
Business Acquisition [Line Items]
Milestone net sales achievement	50,000,000.0
Revenue milestone threshold	200,000,000
Milestone Payment Four [Member]
Business Acquisition [Line Items]
Milestone net sales achievement	100,000,000.0
Revenue milestone threshold	400,000,000
Menadione Topical Lotion [Member]
Business Acquisition [Line Items]
Milestone net sales achievement	5,000,000.0
Talon Therapeutics, Inc. [Member]
Business Acquisition [Line Items]
Cash consideration	$ 11,300,000
Shares issued in acquisition (shares)	3,000,000
Common stock value assigned	$ 26,300,000
Common stock value, per share ($ per share)	$ 8.77
Estimated fair value of acquisition	$ 6,500,000
Contingent value rights future cash payments	$ 195,000,000				$ 195,000,000									195,000,000
Talon Therapeutics, Inc. [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Contingent value rights expected rate	50.00%
Talon Therapeutics, Inc. [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Contingent value rights expected rate	100.00%
Ligand Pharmaceuticals Inc [Member]
Business Acquisition [Line Items]
Ligand Contingent Consideration			6,000,000										6,000,000
Acquisition-related contingent obligations													$ 800,000
Allos Therapeutics, Inc. [Member]
Business Acquisition [Line Items]
Ligand Contingent Consideration					$ 0									$ 0
Total purchase consideration																	$ 205,200,000
Ligand Pharmaceuticals Inc [Member]
Business Acquisition [Line Items]
Milestone net sales achievement		$ 6,000,000	$ 6,000,000