Acquisitions - Summary of Purchase Price Allocation (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Mar. 31, 2013 All 2013 Acquisitions [Member]	Dec. 31, 2012 All 2012 Acquisitions [Member]
Business Acquisition [Line Items]
Trade and other receivables			$ 13,196
Prepaid expenses and other			6,185
Property and equipment			6,701
Goodwill		47,666	165,398
Other intangible assets	109,758	47,666	109,758
Notes and other liabilities assumed		(559)	(42,912)
Deferred tax liabilities			(50,936)
Aggregate purchase price		$ 94,773	$ 207,390