Contract assets and contract liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Contract assets and contract liabilities

Schedule of contract asset, net and contract liability, net balance from customers

	Contract		Contract
	Assets, Net		Liabilities, Net
Balance at December 31, 2019	$	967	$	227,889
Balance at December 31, 2020		547		224,754
Change	$	(420)	$	(3,135)
Balance at December 31, 2018	$	468	$	217,733
Balance at December 31, 2019		967		227,889
Change	$	499	$	10,156

Schedule of remaining performance obligations included in revenue

	Year Ended December 31,
	2020		2019		2018
Amounts included in the beginning of period contract liability balance	$	84,368	$	88,890	$	85,592
Amounts associated with performance obligations satisfied in previous periods		(55)		447		378