Segments and Related Information (Foreign Operations) (Narrative) (Details) - USD ($) $ in Thousands			3 Months Ended		6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segments and Related Information [Line Items]
Revenue			$ 1,617,804	$ 1,890,180	$ 3,014,638	$ 3,048,364
Property and equipment, net	$ 739,425	$ 706,506	739,425		739,425
Intangible assets and goodwill, net	1,328,100	1,328,900	1,328,100		1,328,100
United States [Member]
Segments and Related Information [Line Items]
Revenue			1,600,000	1,800,000	3,000,000	2,900,000
Property and equipment, net	698,600	649,500	698,600		698,600
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			26,700	$ 40,500	60,500	$ 99,700
Property and equipment, net	40,800	57,000	40,800		40,800
Intangible assets and goodwill, net	$ 107,000	$ 112,800	$ 107,000		$ 107,000
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%