Income taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 9,117	$ 1,779
Discrete benefit from stock option exercises	100
Reduction of deferred tax assets	5,100	900
State income tax expense	$ 4,000	$ 900