Summary of Fair Value of Assets Acquired and Liabilities Assumed in Conjunction with Acquisition (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Business Acquisition [Line Items]
Goodwill	$ 129,156		$ 22,522		$ 13,305
Intangible assets with definite lives	111,864	[1]	21,567	[1]	5,211	[1]
Net liabilities	(28,913)	[2]	(590)	[2]	(1,558)	[2]
Total	$ 212,107	[3]	$ 43,499	[3]	$ 16,958	[3]

[1] For 2012, acquired intangible assets primarily consist of customer and supplier relationship assets. In total, the weighted average life of acquired intangible assets during 2012, 2011 and 2010 was 8.1 years, 3.7 years and 3.5 years.

[2] Includes cash acquired of $13 million, $6 million and $1 million during 2012, 2011 and 2010.

[3] As of December 31, 2011, $3 million of the total purchase price was accrued with the remainder paid in cash during the respective years.