Revenue Revenue (Contract Assets and Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable Including Unbilled Receivables	$ 333,044	$ 306,370
Increase (Decrease) in Accounts and Other Receivables	26,674
Contract assets	32,125	32,348
Contract With Customer Asset, Period Change	(223)
Contract liabilities	31,094	$ 34,888
Contract With Customer Liability, Period Change	$ (3,794)