Allowance for Doubtful Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Provision charged to operations:
Non-recoverable balances written off
Allowance for Doubtful Accounts [Member]
Activity in the allowance for doubtful accounts
Balance, January 1	681	372	366
Provision charged to operations:
Additions to the reserve	71	309	37
Collections of previously reserved accounts	(359)		(31)
Total charged (credited) to operations	(288)	309	6
Balance, December 31	$ 393	$ 681	$ 372

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- Definition

Valuation allowances and reserves additions.

+ References

No definition available.

+ Details

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- Definition

Valuation Allowances Non Recoverable Balances Written off.

+ References

No definition available.

+ Details

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- Definition

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.

+ References

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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- Definition

+ References

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- Definition

Total of recoveries of amounts due the Entity that had previously been written off as uncollectible using allowances (the valuation accounts that are netted against the cost of an asset to value it at its carrying value) and total of reestablishments of reserves (liabilities established to represent expected future costs) that had previously been utilized.

+ References

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