Fair Value and Equity Investments, Fair Value (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Fair Value and Equity Investments [Abstract]
Term of variable rate	30 days
Contingent Consideration [Member]
Changes in Fair Value of Level 3 Contingent Consideration [Roll Forward]
Beginning balance	$ (3,125)
Additions from acquisitions	(8,702)
Changes in fair value of contingent consideration	(305)
Ending balance	(12,132)
Fair Value on a Recurring Basis [Member]
Financial Assets (Liabilities) [Abstract]
Cash equivalents and current investments	74,360	$ 56,628
Derivative financial instruments asset	4,395	1,145
Life insurance contracts	48,625	45,453
Derivative financial instruments liability	(112)	(105)
Contingent consideration	(12,132)	(3,125)
Financial assets (liabilities)	115,136	99,996
Fair Value on a Recurring Basis [Member] | Level 1 [Member]
Financial Assets (Liabilities) [Abstract]
Cash equivalents and current investments	74,360	56,628
Derivative financial instruments asset	0	0
Life insurance contracts	0	0
Derivative financial instruments liability	0	0
Contingent consideration	0	0
Financial assets (liabilities)	74,360	56,628
Fair Value on a Recurring Basis [Member] | Level 2 [Member]
Financial Assets (Liabilities) [Abstract]
Cash equivalents and current investments	0	0
Derivative financial instruments asset	4,395	1,145
Life insurance contracts	0	0
Derivative financial instruments liability	(112)	(105)
Contingent consideration	0	0
Financial assets (liabilities)	4,283	1,040
Fair Value on a Recurring Basis [Member] | Level 3 [Member]
Financial Assets (Liabilities) [Abstract]
Cash equivalents and current investments	0	0
Derivative financial instruments asset	0	0
Life insurance contracts	48,625	45,453
Derivative financial instruments liability	0	0
Contingent consideration	(12,132)	(3,125)
Financial assets (liabilities)	36,493	$ 42,328
Life Insurance Contracts [Member]
Changes in Fair Value of Level 3 Marketable Securities [Roll Forward]
Beginning balance	45,453
Actual return on plan assets	3,172
Purchase and issuances	7,016
Sales and settlements	(7,016)
Transfers into Level 3	0
Ending balance	$ 48,625