Business and Basis of Presentation - Schedule of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 189,979	$ 538,908	$ 1,227,891	$ 474,233
Restricted cash classified in:
Prepaid expenses and other current assets	18,143	15,148	25,121	25,121
Other assets	0	3,002	18,150	0
Cash and cash equivalents	19,508	10,000	0	0
Cash and cash equivalents and restricted cash	$ 227,630	$ 567,058	$ 1,271,162	$ 499,354