XML 60 R46.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Investments - Narrative (Details) - USD ($) $ in Millions | Jun. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Investments, Debt and Equity Securities [Abstract] |  |
Restricted investments | $ 117 | $ 119

X
- References No definition available. + Details
Name: | us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition This element represents the noncurrent portion of investments which are not defined as or included in marketable (debt, equity, or other) securities that are pledged or subject to withdrawal restrictions. + References No definition available. + Details
Name: | us-gaap_RestrictedInvestmentsNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant