Schedule of Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Line Items]
Beginning balance, as of January 1	$ 19,678	$ 12,028	$ 12,767
Additions, Tax positions for current year	459	6,131	106
Additions, Tax positions for prior years	1,402	1,296	2,435
Acquired tax positions		1,388
Reductions, Tax positions for prior years	(4,072)	(1,165)	(3,280)
Reductions, Settlements with tax authorities
Ending Balance as of December 31	$ 17,467	$ 19,678	$ 12,028