Segments and Geographic Areas - Reconciliation of Segment Assets to Total Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash and cash equivalents
Total cash and cash equivalents	$ 72,699	$ 133,429	$ 102,498	$ 31,760
Accounts receivable, net
Total accounts receivable, net	239,599	154,255
Goodwill
Total goodwill	471,299	29,492	29,266
Intangible assets, net
Total intangible assets	335,191	13,581
Property and equipment, net
Total property and equipment, net	96,962	80,981
Total assets
Total assets	1,322,249	533,692
CEB [Member]
Cash and cash equivalents
Total cash and cash equivalents	37,715	133,429
Accounts receivable, net
Total accounts receivable, net	194,276	154,255
Goodwill
Total goodwill	80,886	29,492
Intangible assets, net
Total intangible assets	52,124	13,581
Property and equipment, net
Total property and equipment, net	84,360	80,981
Total assets
Total assets	550,429	533,692
SHL [Member]
Cash and cash equivalents
Total cash and cash equivalents	34,984
Accounts receivable, net
Total accounts receivable, net	45,323
Goodwill
Total goodwill	390,413
Intangible assets, net
Total intangible assets	283,067
Property and equipment, net
Total property and equipment, net	12,602
Total assets
Total assets	$ 771,820