Debt (Narrative) (Details)		3 Months Ended
		Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Mar. 31, 2024 GBP (£)	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Average borrowings outstanding		$ 810,700,000	$ 735,000,000
Weighted average interest rate		6.40%	5.80%
Interest Expense, Net		$ (17,150,000)	$ (13,090,000)
Interest expense		19,328,000	14,294,000
5.75% Unsecured Notes maturing in 2026 [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs		$ 1,600,000			$ 1,700,000
Interest rate		5.75%		5.75%	5.75%
Fair value of debt instrument		$ 398,100,000			$ 400,400,000
Five-Year Credit Agreement maturing in 2027 [Member]
Debt Instrument [Line Items]
Credit facility current borrowing capacity		300,000,000
Line of credit facility outstanding		108,126,000			97,879,000
USD revolving credit facility borrowings [Member]
Debt Instrument [Line Items]
Line of credit facility outstanding		45,000,000
GBP revolving credit facility borrowings [Member]
Debt Instrument [Line Items]
Line of credit facility outstanding | £				£ 50,000,000
Term Loan maturing in 2027 - $150 million [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs		700,000			600,000
Loans Payable to Bank	[1]	145,559,000			147,476,000
Real Estate Term Loan maturing in 2028 - $75.2 million [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs		100,000			100,000
Loans Payable to Bank	[2]	73,605,000			74,541,000
Capital Term Loan maturing in 2028 - $65 million [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs		800,000			800,000
Loans Payable to Bank	[3]	$ 61,516,000			$ 63,097,000
Secured Overnight Financing Rates (SOFR) [Member] | USD revolving credit facility borrowings [Member]
Debt Instrument [Line Items]
Applicable interest rate margin		1.375%
Prime Rate [Member] | USD revolving credit facility borrowings [Member]
Debt Instrument [Line Items]
Applicable interest rate margin		0.375%
Sterling Overnight Interbank Average Rate (SONIA) [Member] | GBP revolving credit facility borrowings [Member]
Debt Instrument [Line Items]
Applicable interest rate margin		1.375%
Securities Subject to Mandatory Redemption [Member] | Graham Healthcare Group [Member]
Debt Instrument [Line Items]
Interest expense		$ 1,900,000	$ 1,500,000

[1] The carrying value is net of $0.7 million and $0.6 million of unamortized debt issuance costs as of March 31, 2024 and December 31, 2023, respectively.

[2] The carrying value is net of $0.1 million of unamortized debt issuance costs as of March 31, 2024 and December 31, 2023.

[3] The carrying value is net of $0.8 million of unamortized debt issuance costs as of March 31, 2024 and December 31, 2023.