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Derivative Financial Instruments (Narrative) (Details)	3 Months Ended	9 Months Ended
Derivative Financial Instruments (Narrative) (Details)	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($) bbl	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Derivative [Line Items]
Debt Instrument, Face Amount		$ 4,948,000,000		$ 4,750,000,000
Payments for (Proceeds from) Hedge, Financing Activities		10,444,000	$ 33,342,000
Good Faith and Margin Deposits with Broker-Dealers		14,031,000		27,415,000
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months		$ (3,300,000)
Energy Related Derivative [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| bbl		30,000
Derivative Liability		$ 12,300,000		17,300,000
3.25% Notes Due 2030 [Member]
Derivative [Line Items]
Debt Instrument, Face Amount	$ 500,000,000.0	$ 500,000,000		$ 0
Debt Instrument, Interest Rate, Stated Percentage	3.25%	3.25%
3.25% Notes Due 2030 [Member] \| Cash Flow Hedging [Member] \| Interest Rate Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 100,000,000.0
Payments for (Proceeds from) Hedge, Financing Activities	$ 10,400,000