Financial Instruments (Narrative) (Details)				3 Months Ended	12 Months Ended
	Aug. 16, 2023 USD ($)	Jun. 23, 2023	Oct. 27, 2020 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 18, 2023 USD ($)	Aug. 31, 2023 USD ($)	Jun. 29, 2023 USD ($)	Oct. 17, 2022 USD ($)	Jun. 14, 2021 USD ($)
Debt Instrument [Line Items]
Principal payments due on long-term debt in two years				$ 3,400,000	$ 3,400,000
Principal payments due on long-term debt in three years				1,300,000	1,300,000
Principal payments due on long-term debt in four years				1,200,000	1,200,000
Principal payments due on long-term debt in five years				446,400,000	446,400,000
Principal payments due on long-term debt after five years				400,000	400,000
Cash payments of interest					18,700,000	$ 16,000,000	$ 14,900,000
Total bank debt				456,885,000	456,885,000	439,000,000
Current maturities of long-term debt				4,218,000	4,218,000	0
Interest rate swaps
Debt Instrument [Line Items]
Cash collateral received				0	0
Cash collateral pledged				0	0
Line of Credit
Debt Instrument [Line Items]
Total bank debt				446,000,000	446,000,000	439,000,000
Line of Credit | Interest rate swaps
Debt Instrument [Line Items]
Derivative, notional amount								$ 350,000,000		$ 350,000,000	$ 350,000,000	$ 350,000,000
Derivative, fixed interest rate								5.36%		0.7683%	2.11%	0.838%
All-in SOFR interest rate								2.51%
All-in LIBOR interest rate											3.735%
Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 800,000,000		$ 700,000,000
Debt instrument, term	5 years		4 years
Borrowings outstanding				446,000,000	446,000,000
Line of credit facility, remaining borrowing capacity				$ 354,000,000	$ 354,000,000
Maximum leverage ratio allowed	3.75			3.50	3.50
Maximum leverage ratio allowed after significant acquisition	4.25
Interest coverage ratio	3.00			14.13	14.13
Leverage ratio				1.25	1.25
Debt covenant, maximum annual dividend payout amount					$ 40,000,000
Line of Credit | Unsecured Debt | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on variable rate					1.625%
Line of Credit | Unsecured Debt | Minimum | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on variable rate		0.00%
Foreign Bank Debt
Debt Instrument [Line Items]
Total bank debt				$ 10,885,000	$ 10,885,000	$ 0
Foreign Bank Debt | Heimbach
Debt Instrument [Line Items]
Total bank debt				10,900,000	10,900,000				$ 32,700,000
Repayments of debt				18,600,000
Current maturities of long-term debt				$ 4,200,000	$ 4,200,000
Foreign Bank Debt | Minimum | Heimbach
Debt Instrument [Line Items]
Interest rate, stated percentage									0.98%
Foreign Bank Debt | Maximum | Heimbach
Debt Instrument [Line Items]
Interest rate, stated percentage									5.52%