Business and Basis of Presentation - Schedule of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 141,805	$ 538,908	$ 589,282	$ 474,233
Restricted cash classified in:
Prepaid expenses and other current assets	18,151	15,148	25,130	25,121
Other assets	0	3,002	18,155	0
Cash and cash equivalents	0	10,000	0	0
Cash and cash equivalents and restricted cash	$ 159,956	$ 567,058	$ 632,567	$ 499,354