Reconciliation of Unrecognized Tax Benefits, Excluding Interest and Penalties (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning of period	$ 7,668	$ 7,595	$ 7,776
Additions based on tax positions related to the current year	4,172	1,476	1,891
Additions for tax positions of prior years	6,911	290	1,565
Reductions for tax positions of prior years	(1,061)	(1,005)	(1,544)
Lapse in statute of limitations	(286)	(688)	(2,093)
Settlements	(616)	0	0
Unrecognized tax benefits, end of the period	$ 16,788	$ 7,668	$ 7,595