Revenue Recognition (Contract with Customer, Asset and Liability) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Accounts receivable (including long-term, included in Other assets)	$ 1,019,853	$ 1,081,070
Contract assets, short-term (included in Other current assets)	7,536	9,830
Contract assets, long-term (included in Other assets)	942	942
Contract liabilities (Deferred revenue)	$ 76,787	$ 71,048