v3.19.2

Revenue From Contracts with Customers Performance Obligations and Contract Balances (Details) - Environmental Credits [Member] - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018 | Dec. 31, 2018
Disaggregation of Revenue [Line Items] |  |  |  |  |
Deferred Revenue, Current | $ 22 |  | $ 22 |  | $ 14
Deferred Revenue, Revenue Recognized | $ 2 | $ 3 | $ 3 | $ 9 |

X
- Definition Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable, classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(5)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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Balance Type: | credit
Period Type: | instant

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- Definition Amount of revenue recognized that was previously reported as deferred or unearned revenue. + References No definition available. + Details
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Balance Type: | credit
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- 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
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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |