Income taxes (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 134,531
Unrecognized tax benefits that would impact effective tax rate if recognized	134,531
Accrued interest related to the gross unrecognized tax benefits excluded from the unrecognized tax benefits	25,287
Decrease in unrecognized tax benefits that is reasonably possible (up to)	$ 100,000