Allowance for Doubtful Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for doubtful accounts
Balance, beginning of year	$ 3,686	$ 3,780	$ 4,585
Provision (net of recovery)	(306)	1,001	(23)
Amounts written off, net of recoveries	(1,536)	(1,095)	(782)
Balance, end of year	$ 1,844	$ 3,686	$ 3,780