v3.19.3

Derivative Financial Instruments (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) bbl	Mar. 31, 2019 USD ($)	Sep. 30, 2019 USD ($) bbl	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Derivative [Line Items]
Debt Instrument, Face Amount	$ 4,750,000,000		$ 4,750,000,000		$ 4,300,000,000
Net receipt (payment) on financial derivatives			(33,342,000)	$ 20,925,000
Good Faith and Margin Deposits with Broker-Dealers	21,811,000		21,811,000		0
Energy commodity derivatives deposits	0		0		37,328,000
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ (3,200,000)		$ (3,200,000)
Energy Related Derivative [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl	30,000		30,000
Derivative Liability	$ 17,800,000		$ 17,800,000
Three Point Nine Five Percentage Notes Due Two Thousand Fifty [Member]
Derivative [Line Items]
Debt Instrument, Face Amount	$ 500,000,000.0		$ 500,000,000.0		0
Debt Instrument, Interest Rate, Stated Percentage	3.95%		3.95%
Three Point Nine Five Percentage Notes Due Two Thousand Fifty [Member] | Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net receipt (payment) on financial derivatives	$ (25,300,000)
4.85% Notes Due 2049 [Member]
Derivative [Line Items]
Debt Instrument, Face Amount	$ 500,000,000	$ 500,000,000.0	$ 500,000,000		$ 0
Debt Instrument, Interest Rate, Stated Percentage	4.85%	4.85%	4.85%
4.85% Notes Due 2049 [Member] | Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net receipt (payment) on financial derivatives		$ (8,000,000.0)

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of right to receive cash and securities on deposit with broker-dealers to demonstrate an intention to complete a purchase (good faith deposit) and collateral deposited by counterparty to cover the credit risk assumed (margin deposit).

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