Reconciliation of Beginning and Ending Balances of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits [Line Items]
Balance as of January 1,	$ 23,972	$ 43,396	$ 40,929
Additions based on tax positions related to the current year	80	817	4,041
Additions for tax positions of prior years	110	183	285
(Reductions) Additions for acquired uncertain tax benefits	387		(716)
Reductions for tax positions of prior years	(1,541)	(19,855)	(853)
Reductions for a lapse of the applicable statute of limitations	(337)	(569)	(290)
Balance as of December 31,	$ 22,671	$ 23,972	$ 43,396