Significant Accounting Policies - Allowance for Doubtful Accounts Receivable (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning Balance	$ 1,738		$ 1,412		$ 1,571
Charged to costs and expenses	1,900		1,038		482
Charged to other accounts	292	[1]	479	[1]	563	[1]
Deductions	(1,269)	[2]	(1,191)	[2]	(1,204)	[2]
Ending Balance	$ 2,661		$ 1,738		$ 1,412

[1] Recovery of receivables previously written off as bad debt

[2] Write-off of uncollectible accounts receivable