Segment Reporting and Information about Geographic Areas - Schedule of Long-Lived Assets by Geographic Area (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived Assets	$ 17,547,832	$ 16,375,012
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived Assets	16,716,027	15,587,979
International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived Assets	$ 831,805	$ 787,033