Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for doubtful accounts
Balance, beginning of year	$ 1,844	$ 3,686	$ 3,780
Provision (net of recovery)	346	(306)	1,001
Amounts written off, net of recoveries	(773)	(1,536)	(1,095)
Balance, end of year	$ 1,417	$ 1,844	$ 3,686