Segment Information (Details) - Summarized Information by Geographic Location - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Revenues	$ 3,311,494	$ 2,444,540	$ 2,163,056
Long-lived assets:
Long-lived assets	415,249	210,877	211,113
United States and Canada
Revenues:
Revenues	2,037,111	1,519,748	1,347,676
Long-lived assets:
Long-lived assets	288,735	143,921	163,933
Europe, Middle East and Africa
Revenues:
Revenues	850,352	616,721	557,165
Long-lived assets:
Long-lived assets	84,840	42,326	31,130
Other International
Revenues:
Revenues	424,031	308,071	258,215
Long-lived assets:
Long-lived assets	$ 41,674	$ 24,630	$ 16,050