Supplemental balance sheet and cash flow information (trade accounts receivable, allowance for credit losses) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Trade accounts receivable
Trade accounts receivable - gross		$ 178,829		$ 197,546
Allowance for credit losses		(7,560)		(6,541)
Trade accounts receivable - net	[1]	171,269		191,005
Unbilled receivables		51,408		$ 43,673
Changes in allowance for credit losses
Balance, beginning of year		6,541	$ 4,182
Bad debt expense		2,960	1,466
Write-offs and other		(1,941)	(824)
Balance, end of period		$ 7,560	$ 4,824

[1] Includes unbilled receivables of $51,408 as of March 31, 2024 and $43,673 as of December 31, 2023.