Revenue Recognition - Contract Balances with Customers (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Trade accounts receivable and contract assets, net:
Trade accounts receivable	$ 151,589		$ 156,648
Contract assets	46,938		63,758
Allowance for doubtful accounts	(10,608)		(23,777)
Total trade accounts receivable and contract assets, net	187,919		196,629
Contract liabilities:
Current	99,266		101,060
Noncurrent	9,426		10,572
Total contract liabilities	108,692		111,632
Revenue recognized	52,200	$ 39,500
Sales and services
Trade accounts receivable and contract assets, net:
Trade accounts receivable	147,288		152,632
Leasing
Trade accounts receivable and contract assets, net:
Trade accounts receivable	$ 4,301		$ 4,016