Segment Information (Detail) - Summarized Information by Geographic Location - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
Revenues	$ 2,163,056	$ 2,021,441	$ 1,784,213
Long-lived assets:
Long-lived assets	211,113	190,338	172,176
United States and Canada
Revenues:
Revenues	1,347,676	1,204,476	1,049,734
Long-lived assets:
Long-lived assets	163,933	142,963	123,877
Europe, Middle East and Africa
Revenues:
Revenues	557,165	570,334	508,755
Long-lived assets:
Long-lived assets	31,130	34,093	34,363
Other International
Revenues:
Revenues	258,215	246,631	225,724
Long-lived assets:
Long-lived assets	$ 16,050	$ 13,282	$ 13,936