Debt and Financing Arrangements (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term Debt	$ 579,030	$ 578,018
Issuance of debt	3,059	3,581
Debt Instrument, Unamortized Discount	2,911	3,401
Long-term Debt, Fiscal Year Maturity [Abstract]
2025	85,000
7.125 percent unsecured debentures due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt	85,000	85,000
4.0% unsecured debentures due 2027 [Member]
Debt Instrument [Line Items]
Long-term Debt	500,000	$ 500,000
Asset Pledged as Collateral [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 0