Banking Facilities and Debt (Details) $ in Thousands			12 Months Ended
	Aug. 03, 2023 USD ($)	May 07, 2015	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Summary of outstanding debt
Total Debt			$ 0	$ 0
Maximum
Banking facilities and other debt
Pro forma Cash Flow Leverage Ratio to be maintained to purchase, redeem or otherwise acquire shares of common stock			3.00
Cash flow leverage ratio		3.50
Revolving Facilities
Banking facilities and other debt
Maximum borrowing capacity	$ 75,000
Accordion feature period	4 years
Maximum borrowing capacity accordion feature	$ 50,000
Revolving Facilities | SOFR
Banking facilities and other debt
Interest rate margin (as a percent)	0.10%
Revolving Facilities | Minimum
Banking facilities and other debt
Commitment fee (as a percent)	0.225%
Revolving Facilities | Minimum | Lender's prime rate
Banking facilities and other debt
Interest rate margin (as a percent)	0.00%
Revolving Facilities | Minimum | SOFR
Banking facilities and other debt
Interest rate margin (as a percent)	1.00%
Revolving Facilities | Maximum
Banking facilities and other debt
Commitment fee (as a percent)	0.35%
Revolving Facilities | Maximum | Lender's prime rate
Banking facilities and other debt
Interest rate margin (as a percent)	1.00%
Revolving Facilities | Maximum | SOFR
Banking facilities and other debt
Interest rate margin (as a percent)	2.00%
Letter of Credit
Banking facilities and other debt
Maximum borrowing capacity	$ 10,000
Revolving Facility
Banking facilities and other debt
Letters of credit outstanding			$ 541