Revenue Recognition (Contract Balances) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Receivables, which are included in accounts receivable - trade, net	$ 2,194		$ 2,194		$ 2,129
Contract assets, net, which are included in other current assets	5,965		5,965		8,766
Payables, which are included in other current liabilities	1,544		1,544		1,663
Contract liabilities, which are included in other current liabilities	9,725		9,725		9,358
Contract assets, net, which are included in other assets	26,083		26,083		18,443
Contract liabilities, which are included in other liabilities	28,304		28,304		$ 29,045
Revenue recognized on contract liabilities	$ 1,451		$ 8,109
Revenue recognized relating to performance obligations satisfied or partially satisfied in prior periods		$ 4,722		$ 9,753