Summary of Allowance for Doubtful Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	$ 2,022	$ 2,168	$ 2,407
Provision		53	1,014
Write-offs, net of recoveries	(1,319)	(199)	(1,253)
Balance, end of year	$ 703	$ 2,022	$ 2,168