XML 78 R59.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Cash and Investments (Narrative) (Details) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 28, 2018 USD ($) investment | Dec. 28, 2018 USD ($) investment | Dec. 29, 2017 USD ($) investment | Dec. 30, 2016 USD ($) | Jan. 01, 2016 USD ($) | Aug. 31, 2016
Investment [Line Items] |  |  |  |  |  |
Gain (loss) on sales of investments available-for-sale |  |  |  | $ 0 | $ 0 |
Number of investments in an unrealized loss position | investment | 199 | 199 | 134 |  |  |
Other-than-temporary impairment charges on available-for-sale securities |  |  | $ 0 | 0 | $ 0 |
Beneficial ownership interest by BlackRock (more than) | 10.00% | 10.00% |  |  |  |
Fair value of cash and investments managed by BlackRock | $ 298,500,000 | $ 298,500,000 | 141,000,000 |  |  |
Fair value of cash and investments managed by BlackRock in the BlackRock Liquidity Money Market Fund | 3,000,000 | 3,000,000 | 1,000,000 |  |  |
Fees for advisory services paid to BlackRock | $ 200,000 |  |  |  |  |
Akarna Therapeutics, Ltd. |  |  |  |  |  |
Investment [Line Items] |  |  |  |  |  |
Realized gain on sale of cost method investment |  | $ 200,000 |  |  |  |
Realized gain on sale of cost method investment |  |  | $ 3,000,000 | $ 2,500,000 |  |
Cost method investment ownership percentage |  |  |  |  |  | 9.00%

X
- Definition Cost Method Investment, Ownership Percentage + References No definition available. + Details
Name: | exel_CostMethodInvestmentOwnershipPercentage
Namespace Prefix: | exel_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Minority Ownership, Ownership Interest + References No definition available. + Details
Name: | exel_OwnershipInterestByMinorityShareholder
Namespace Prefix: | exel_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Related Party Transactions, Advisory Fees Paid + References No definition available. + Details
Name: | exel_RelatedPartyTransactionsAdvisoryFeesPaid
Namespace Prefix: | exel_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Related Party Transactions, Cash And Investments Managed By Minority Owner + References No definition available. + Details
Name: | exel_RelatedPartyTransactionsCashAndInvestmentsManagedByMinorityOwner
Namespace Prefix: | exel_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Related Party Transactions, Cash And Investments Managed By Minority Owner, Invested In Money Market Fund + References No definition available. + Details
Name: | exel_RelatedPartyTransactionsCashAndInvestmentsManagedByMinorityOwnerInvestedInMoneyMarketFund
Namespace Prefix: | exel_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line items represent reporting 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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 12 -Sentence Column A + Details
Name: | invest_InvestmentLineItems
Namespace Prefix: | invest_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition This item represents the gain (loss) realized during the period from the sale of investments accounted for under the cost method of accounting and any losses recognized thereon for impairments of other than a temporary nature. + References No definition available. + Details
Name: | us-gaap_CostMethodInvestmentsRealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 321 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84241550&loc=SL75117546-209714 + Details
Name: | us-gaap_EquitySecuritiesFvNiRealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of other-than-temporary impairment (OTTI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), recognized in earnings and other comprehensive loss (OCI). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 8A -URI http://asc.fasb.org/extlink&oid=109979856&loc=SL6284422-111562 + Details
Name: | us-gaap_OtherThanTemporaryImpairmentLossDebtSecuritiesAvailableForSale
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | invest_InvestmentAxis=exel_AkarnaTherapeuticsLtd.Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |