Segments and Related Information (Foreign Operations) (Narrative) (Details) - USD ($) $ in Thousands				3 Months Ended								12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment and Related Information [Line Items]
Revenue				$ 1,602,900	$ 1,955,800	$ 1,890,200	$ 1,158,200	$ 1,341,900	$ 1,586,200	$ 1,232,400	$ 974,200	$ 6,606,978	$ 5,134,703	$ 4,208,330
Property and equipment, net	$ 706,506	$ 549,084		706,506				549,084				706,506	549,084
Intangible assets and goodwill, net	1,328,900	1,175,600		1,328,900				1,175,600				1,328,900	1,175,600
United States [Member]
Segment and Related Information [Line Items]
Revenue												6,400,000	4,900,000	3,600,000
Property and equipment, net	649,500	475,300	$ 464,600	649,500				475,300				649,500	475,300	464,600
Intangible assets and goodwill, net	1,200,000	1,100,000	1,100,000	1,200,000				1,100,000				1,200,000	1,100,000	1,100,000
Foreign Operations [Member]
Segment and Related Information [Line Items]
Revenue												211,500	279,700	574,800
Property and equipment, net	57,000	73,800	94,100	57,000				73,800				57,000	73,800	94,100
Intangible assets and goodwill, net	$ 112,800	$ 107,800	$ 107,300	$ 112,800				$ 107,800				$ 112,800	$ 107,800	$ 107,300
Foreign Operations [Member] | Accounts Receivable, Net, Less BIEC [Member] | Geographic Concentration Risk [Member] | Foreign Customers [Member]
Segment and Related Information [Line Items]
Concentration risk, percentage of total	5.00%	8.00%	17.00%