Summary of Significant Accounting Policies (Additional Cash Flow) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Noncash or Part Noncash Acquisitions [Line Items]
Total net adjustment	$ 4,400	$ 8,900	$ 11,600
Adjustments to other comprehensive income related to underfunding of pension and SERP plans and changes in fair value of derivative financial instruments, tax	1,300	2,600	3,700
Dividends declared but not yet paid	5,500	5,600	5,600
Accrual for purchases of property and equipment		800	2,900
Gain (Loss) on Disposition of Business	493	(3,739)	5,722
Gain (Loss) on Disposition of Business, Non Cash	$ 493	(3,971)	(5,722)
Notes Reduction		4,000
Notes Issued			$ 2,500
Value of consideration received		3,100
Options issued in debt conversion (in shares)			114,778
Stock conversion amount			$ 7,600
Other Significant Noncash Transaction, Value of Consideration Given		1,700
Distribution [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Gain (Loss) on Disposition of Business		$ 4,000
2017 Notes
Noncash or Part Noncash Acquisitions [Line Items]
Options issued in debt conversion (in shares)			114,778