Contract balances (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Contract assets	$ 185,086		$ 185,086		$ 104,345
Change in contract assets			80,741
Contract liabilities - current	(153,408)		(153,408)		(158,603)
Change in contract liabilities - current			5,195
Contract liabilities - noncurrent	(157)		(157)		(52)
Change in contract liabilities - noncurrent			(105)
Net contract assets (liabilities)	31,521		31,521		$ (54,310)
Change in net contract assets (liabilities)			85,831
Amounts included in contract liability at the beginning of the period	7,100	$ 15,600	152,400	$ 137,300
Amounts from performance obligations satisfied in prior periods	$ 19,200	$ 34,700	$ 63,300	$ 58,800