Revenue Recognition Contract Balances with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Receivables from Customers	$ 33,205		$ 33,205		$ 52,140
Contract with Customer, Asset, Net, Current	18		18
Contract with Customer, Asset, Net, Noncurrent	3,255		3,255		2,614
Contract with Customer, Liability, Current	774		774		$ 480
Increase (Decrease) in Receivables			(18,935)
Increase (Decrease) in Other Current Assets			18
Increase (Decrease) in Other Noncurrent Assets			641
Increase (Decrease) in Other Current Liabilities			294
Contract with Customer, Liability, Revenue Recognized	$ 200	$ 100	$ 700	$ 400