Indebtedness (Schedule of Indebtedness Outstanding) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term Debt	$ 1,836,662	$ 1,336,662
Debt Issuance Costs, Noncurrent, Net	(406)	(593)
Long-term debt	1,611,256	1,336,069
Long-term Debt, Net of Debt Issuance Costs	1,836,256	1,336,069
Long-term Debt, Current Maturities	225,000	0
Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 600,000	600,000
Debt Instrument, Maturity Date	Dec. 30, 2026
Senior Notes - Series 2021-A due March 24, 2026
Debt Instrument [Line Items]
Long-term Debt	$ 100,000	0
Debt Instrument, Maturity Date	Mar. 24, 2026
Senior Notes - Series 2021-B due March 24, 2031
Debt Instrument [Line Items]
Long-term Debt	$ 400,000	0
Debt Instrument, Maturity Date	Mar. 24, 2031
Senior Notes - Series 2020-A due March 11, 2030
Debt Instrument [Line Items]
Long-term Debt	$ 300,000	300,000
Debt Instrument, Maturity Date	Mar. 11, 2030
Senior Notes - Series 2015-A due February 15, 2022
Debt Instrument [Line Items]
Long-term Debt	$ 225,000	225,000
Debt Instrument, Maturity Date	Feb. 15, 2022
Senior Notes - Series 2015-B due February 14, 2025
Debt Instrument [Line Items]
Long-term Debt	$ 200,000	200,000
Debt Instrument, Maturity Date	Feb. 14, 2025
Other [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 11,662	$ 11,662
Debt Instrument, Maturity Date	Sep. 01, 2025

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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.

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Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

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Amount, after accumulated amortization, of debt issuance costs classified as noncurrent. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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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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