Revenue Recognition (Contract Balances) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($)
Trade accounts receivable, net
Balance, January 1, 2021	$ 18,894
Balance, June 30, 2021	21,277
Increase (decrease) in trade accounts receivables, net	2,383
Contract asset (long-term)
Balance, January 1, 2021	4,984
Balance, June 30, 2021	5,321
Increase (decrease) in contract asset (long-term)	337
Contract liability (current)
Balance, January 1, 2021	941
Balance, June 30, 2021	868
Increase (decrease) in contract liability (current)	(73)
Contract liability (long-term)
Balance, January 1, 2021	3,626
Balance, June 30, 2021	4,113
Increase (decrease) in contract liability (long-term)	$ 487