Segment Information (Detail) - Summarized Information by Geographic Location (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Revenues:
Revenues	$ 1,615,808		$ 1,468,588		$ 1,288,454
Long-lived assets: (1)
Long-lived assets	162,480		119,621		97,194
United States and Canada [Member]
Revenues:
Revenues	947,075		861,481		765,793
Long-lived assets: (1)
Long-lived assets	114,557	[1],[2]	85,194	[1],[2]	69,163	[1],[2]
Europe, Middle East, and Africa [Member]
Revenues:
Revenues	458,675		437,194		380,771
Long-lived assets: (1)
Long-lived assets	30,967	[1]	23,673	[1]	21,856	[1]
Other International [Member]
Revenues:
Revenues	210,058		169,913		141,890
Long-lived assets: (1)
Long-lived assets	$ 16,956	[1]	$ 10,754	[1]	$ 6,175	[1]

[1] Excludes goodwill and other intangible assets.

[2] The 2012 balance for the United States and Canada includes approximately $17.0 million of additional costs capitalized in 2012 in connection with the renovation of the Company's Stamford headquarters facility (see Note 1 - Business and Significant Accounting Policies for additional description).