Revenue recognition - Summary of Deferred Revenue Balances by Reportable Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Total deferred revenue	$ 297,166	$ 293,544	$ 282,414
Enterprise
Disaggregation of Revenue [Line Items]
Total deferred revenue	245,717	233,466	220,127
Consumer
Disaggregation of Revenue [Line Items]
Total deferred revenue	$ 51,449	$ 60,078	$ 62,287