Long-term Debt (Summary of Long-Term Debt) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Feb. 08, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term debt	$ 2,875,000		$ 2,875,000
Unamortized discount	(25,321)		(18,337)
Unamortized deferred financing costs	(15,015)		(7,356)
Long-term debt, net	2,834,664		2,849,307
Current portion of long-term debt	16,875		75,000
Noncurrent portion of long-term debt	2,817,789		2,774,307
Senior Notes \| 4.75% Notes due December 2022
Debt Instrument [Line Items]
Long-term debt	$ 0		400,000
Interest rate	4.75%	4.75%
Senior Notes \| 5.00% Notes due April 2024
Debt Instrument [Line Items]
Long-term debt	$ 400,000		1,000,000
Interest rate	5.00%	5.00%
Senior Notes \| 4.75% Notes due August 2025
Debt Instrument [Line Items]
Long-term debt	$ 800,000		800,000
Interest rate	4.75%
Senior Notes \| 4.25% Notes due February 2029
Debt Instrument [Line Items]
Long-term debt	$ 1,000,000		0
Interest rate	4.25%	4.25%
Secured debt \| Term Loan A Facility
Debt Instrument [Line Items]
Long-term debt	$ 675,000		$ 675,000
Revolving credit facility
Debt Instrument [Line Items]
Remaining undrawn capacity	$ 500,000

Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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

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Amount, after accumulated amortization, of debt discount.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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