Segment and Geographic Information Schedule of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues from External Customers and Long-Lived Assets
Revenues	$ 3,147,773	$ 3,122,378	$ 9,496,249	$ 8,873,893
UNITED STATES
Revenues from External Customers and Long-Lived Assets
Revenues	1,579,691	1,535,557	4,735,134	4,716,927
UNITED KINGDOM
Revenues from External Customers and Long-Lived Assets
Revenues	394,621	408,474	1,217,199	1,294,155
GERMANY
Revenues from External Customers and Long-Lived Assets
Revenues	394,115	415,748	1,196,527	564,698
Other countries
Revenues from External Customers and Long-Lived Assets
Revenues	$ 779,346	$ 762,599	$ 2,347,389	$ 2,298,113