Accounts Receivable - Summary of Activity in Allowances for Doubtful Accounts, Returns and Discounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Valuation and Qualifying Accounts Disclosure [Line Items]
Activity in allowances for doubtful accounts, Balance at Beginning of Period	$ 8,252	$ 5,897	$ 5,163
Activity in allowances for doubtful accounts, Charges to Revenue	3,141	2,620	1,533
Activity in allowances for doubtful accounts, Charges (Credits) to Expense	461	615	1,056
Activity in allowances for doubtful accounts, Additions to (Deductions from) Reserves	(2,259)	(880)	(1,855)
Activity in allowances for doubtful accounts, Balance at End of Period	$ 9,595	$ 8,252	$ 5,897

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 09

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e24092-122690

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Total of the deductions in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, representing receivables written off as uncollectible and portions of the reserves utilized, respectively.

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