Segment Information (Detail) - Summarized Information by Geographic Location (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues:
Revenues	$ 2,021,441		$ 1,784,213		$ 1,615,808
Long-lived assets:
Long-lived assets	190,338	[1]	172,176	[1]	162,480	[1]
United States and Canada
Revenues:
Revenues	1,204,476		1,049,734		947,075
Long-lived assets:
Long-lived assets	142,963	[1]	123,877	[1]	114,557	[1]
Europe, Middle East and Africa
Revenues:
Revenues	570,334		508,755		458,675
Long-lived assets:
Long-lived assets	34,093	[1]	34,363	[1]	30,967	[1]
Other International
Revenues:
Revenues	246,631		225,724		210,058
Long-lived assets:
Long-lived assets	$ 13,282	[1]	$ 13,936	[1]	$ 16,956	[1]

[1] Excludes goodwill and other intangible assets.