Revenue Recognition (Contract with Customer, Asset and Liability) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Accounts receivable (including long-term, included in Other assets)	$ 1,042,312	$ 1,018,105
Contract assets, short-term (included in Other current assets)	15,767	9,131
Contract assets, long-term (included in Other assets)	8,696	8,136
Contract liabilities (Deferred revenue)	$ 56,577	$ 55,424