Revenue Recognition (Contract Balances) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Trade accounts receivable, net
Balance, January 1, 2019	$ 20,817
Balance, September 30, 2019	13,540
Increase (decrease) in accounts receivable	(7,277)
Contract liability (current)
Balance, January 1, 2019	754
Balance, September 30, 2019	726
Increase (decrease) in contract liability (current)	(28)
Contract liability (long-term)
Balance, January 1, 2019	2,008
Balance, September 30, 2019	1,543
Increase (decrease) in contract liability (long-term)	$ (465)