Segments and Related Information (Foreign Operations) (Narrative) (Details) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segments and Related Information [Line Items]
Revenue			$ 1,977,227	$ 1,955,752	$ 4,991,865	$ 5,004,116
Property and equipment, net	$ 736,447	$ 706,506	736,447		736,447
Intangible assets and goodwill, net	1,327,000	1,328,900	1,327,000		1,327,000
United States [Member]
Segments and Related Information [Line Items]
Revenue			1,900,000	1,900,000	4,900,000	4,800,000
Property and equipment, net	697,500	649,500	697,500		697,500
Intangible assets and goodwill, net	1,200,000	1,200,000	1,200,000		1,200,000
Foreign Operations [Member]
Segments and Related Information [Line Items]
Revenue			41,400	$ 61,000	101,900	$ 160,700
Property and equipment, net	38,900	57,000	38,900		38,900
Intangible assets and goodwill, net	$ 108,400	$ 112,800	$ 108,400		$ 108,400
Foreign Operations [Member] | Accounts Receivable, Net, Less BIEC [Member] | Geographic Concentration Risk [Member]
Segments and Related Information [Line Items]
Concentration risk, percentage of total	3.00%	5.00%