v3.20.1

Derivative Financial Instruments (Narrative) (Details) | 12 Months Ended
--- | ---
Dec. 31, 2019 USD ($) bbl | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Derivative [Line Items] |  |  |
Commodity derivatives deposits | $ 27,415,000 | $ 0 |
Debt Instrument, Face Amount | 4,750,000,000 | 4,300,000,000 |
Net payment on financial derivatives | 33,342,000 | (24,619,000) | $ 0
Commodity derivatives deposits | 0 | 37,328,000 |
Interest Expense [Member] |  |  |
Derivative [Line Items] |  |  |
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months | (3,200,000) |  |
3.95% Notes due 2050 [Member] |  |  |
Derivative [Line Items] |  |  |
Debt Instrument, Face Amount | $ 500,000,000.0 | 0 |
Debt Instrument, Interest Rate, Stated Percentage | 3.95% |  |
Net payment on financial derivatives | $ 25,300,000 |  |
4.85% Notes Due 2049 [Member] |  |  |
Derivative [Line Items] |  |  |
Debt Instrument, Face Amount | $ 500,000,000.0 | 0 |
Debt Instrument, Interest Rate, Stated Percentage | 4.85% |  |
Net payment on financial derivatives | $ 8,000,000.0 |  |
Interest Rate Contract [Member] | Future Debt Issuance 2018 [Member] | Cash Flow Hedging [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative, Notional Amount |  | 200,000,000.0 |
Net payment on financial derivatives |  | $ (24,600,000) |
Energy Related Derivative [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative, Nonmonetary Notional Amount | bbl | 30,000 |  |
Derivative Liability | $ 17,300,000 |  |

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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + 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 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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