Summary of Significant Accounting Policies - Allowance for Doubtful Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning Balance	$ 1,208	$ 671	$ 898
Provision for Credit Losses	968	1,160	1,883
Charge-offs	(1,604)	(623)	(2,110)
Ending Balance	$ 572	$ 1,208	$ 671