Intangible Assets, Net (Gross and Net Carrying Amounts for each Major Class of Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 6,647,824	$ 6,761,075
Accumulated amortization	(3,491,674)	(3,134,302)
Net book value	3,156,150	3,626,773
Current Contract Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	4,876,880	4,996,591
Accumulated amortization	(2,471,438)	(2,218,404)
Net book value	2,405,442	2,778,187
Network Location Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,770,944	1,764,484
Accumulated amortization	(1,020,236)	(915,898)
Net book value	$ 750,708	$ 848,586