Reconciliation of Beginning and Ending Amount of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Uncertain tax positions, Beginning balance	$ 1,180	$ 1,180	$ 1,180
Increases during the year	0	0	0
Decreases during the year	0	0	0
Uncertain tax positions, Ending balance	$ 1,180	$ 1,180	$ 1,180