XML 38 R45.htm IDEA: XBRL DOCUMENT
v3.19.3

Financial Instruments and Fair Value Measurements - Summary of Financial Instruments by Significant Categories and Fair Value Measurement on a Recurring Basis (Details) - USD ($) $ in Millions | Sep. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Fair Value, Financial Instruments [Line Items] |  |
Total unrestricted and restricted cash equivalents and investments | $ 1,194 | $ 1,546
Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Cash equivalents | 55 | 5
Investments | 194 | 189
Restricted cash equivalents | 61 | 68
Restricted investments | 1 | 8
Total unrestricted and restricted cash equivalents and investments | 311 | 270
Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Cash equivalents | 51 | 4
Investments | 0 | 0
Restricted cash equivalents | 61 | 68
Restricted investments | 1 | 1
Total unrestricted and restricted cash equivalents and investments | 113 | 73
Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Cash equivalents | 4 | 1
Investments | 194 | 189
Restricted cash equivalents | 0 | 0
Restricted investments | 0 | 7
Total unrestricted and restricted cash equivalents and investments | 198 | 197
Asset-backed securities | Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 30 | 33
Asset-backed securities | Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 0 | 0
Asset-backed securities | Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 30 | 33
Corporate bonds | Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 98 | 99
Corporate bonds | Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 0 | 0
Corporate bonds | Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 98 | 99
U.S. government agencies and government- sponsored agencies | Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 5 | 7
U.S. government agencies and government- sponsored agencies | Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 0 | 0
U.S. government agencies and government- sponsored agencies | Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 5 | 7
U.S. treasuries | Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 54 | 41
Restricted investments | 0 | 5
U.S. treasuries | Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 0 | 0
Restricted investments | 0 | 0
U.S. treasuries | Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 54 | 41
Restricted investments | 0 | 5
Other debt securities | Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 7 | 9
Other debt securities | Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 0 | 0
Other debt securities | Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Investments | 7 | 9
Exchange traded fund | Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Restricted investments | 1 | 1
Exchange traded fund | Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Restricted investments | 1 | 1
Exchange traded fund | Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Restricted investments | 0 | 0
Certificate of deposit |  |
Fair Value, Financial Instruments [Line Items] |  |
Total unrestricted and restricted cash equivalents and investments |  | 2
Certificate of deposit | Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Restricted investments | 0 | 2
Certificate of deposit | Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Restricted investments | 0 | 0
Certificate of deposit | Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Restricted investments | 0 | 2
Money market mutual funds | Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Cash equivalents | 51 | 4
Restricted cash equivalents | 43 | 48
Money market mutual funds | Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Cash equivalents | 51 | 4
Restricted cash equivalents | 43 | 48
Money market mutual funds | Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Cash equivalents | 0 | 0
Restricted cash equivalents | 0 | 0
U.S. treasuries | Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Cash equivalents | 4 | 1
U.S. treasuries | Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Cash equivalents | 0 | 0
U.S. treasuries | Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Cash equivalents | 4 | 1
Commercial paper | Fair Value Measurement on a Recurring Basis |  |
Fair Value, Financial Instruments [Line Items] |  |
Restricted cash equivalents | 18 | 20
Commercial paper | Fair Value Measurement on a Recurring Basis | Level 1 |  |
Fair Value, Financial Instruments [Line Items] |  |
Restricted cash equivalents | 18 | 20
Commercial paper | Fair Value Measurement on a Recurring Basis | Level 2 |  |
Fair Value, Financial Instruments [Line Items] |  |
Restricted cash equivalents | $ 0 | $ 0

X
- Definition Amount of 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/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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
Name: | us-gaap_CashEquivalentsAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet. + References No definition available. + Details
Name: | us-gaap_RestrictedCashAndInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of cash equivalents restricted as to withdrawal or usage. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(2)) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=98513485&loc=SL98516268-108586 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(1)(a)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_RestrictedCashEquivalents
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The aggregate value of all restricted investments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-12C.9(c)) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611225-123010 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-12.6(c)) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010 + Details
Name: | us-gaap_RestrictedInvestmentsAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_OtherDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_ExchangeTradedFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_CertificatesOfDepositMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CashAndCashEquivalentsAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CashAndCashEquivalentsAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CashAndCashEquivalentsAxis=us-gaap_CommercialPaperMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |