Schedule of Tangible Long-Lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets
Long-lived Assets	$ 1,201,003	$ 913,089
UNITED STATES
Revenues from External Customers and Long-Lived Assets
Long-lived Assets	609,562	583,236
UNITED KINGDOM
Revenues from External Customers and Long-Lived Assets
Long-lived Assets	170,940	178,021
Other countries
Revenues from External Customers and Long-Lived Assets
Long-lived Assets	210,157	151,791
GERMANY
Revenues from External Customers and Long-Lived Assets
Long-lived Assets	$ 210,344	$ 41