Share-based compensation - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Share-based compensation
Income tax benefit from compensation expense	$ (100,000)	$ 0	$ 400,000	$ 200,000
Restricted stock units
Share-based compensation
Fair value of vested stock			500,000	1,400,000
Income tax benefit from compensation expense			100,000	300,000
Unrecognized share based compensation	300,000		$ 300,000
Weighted average period for recognition of unrecognized compensation cost (in years)			4 months 24 days
Long-term Incentive Plan
Share-based compensation
Payment award, low end of range			0.00%
Payment award, high end of range			220.00%
Measurement period for total return to shareholders (in years)			3 years
Award performance period (in years)			3 years
LTIP linked to TRS
Share-based compensation
Fair value of vested stock			$ 0	0
Unrecognized share based compensation	4,400,000		$ 4,400,000
Weighted average period for recognition of unrecognized compensation cost (in years)			2 years 1 month 6 days
LTIP awards linked to other performance conditions
Share-based compensation
Fair value of vested stock				1,700,000
Income tax benefit from compensation expense				$ 400,000
Unrecognized share based compensation	$ 2,000,000.0		$ 2,000,000.0
Weighted average period for recognition of unrecognized compensation cost (in years)			1 year 2 months 12 days
Equity and Incentive Plan
Share-based compensation
Shares available for future issuance (in shares)	2,500,000		2,500,000
Number of share issuable upon vesting and achievement of performance goals (in shares)	1,300,000		1,300,000
Nonemployee Director Stock Plan
Share-based compensation
Shares available for future grant (in shares)	41,964		41,964