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Concentrations of Credit Risk and Major Customers (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2011 Customer | Dec. 31, 2010 Customer | Dec. 31, 2009 Customer
Concentration Risk |  |  |
Concentration of risk, number of customers | 5 |  |
Sales Revenue, Services, Net [Member] | Customer Concentration Risk [Member] |  |  |
Concentration Risk |  |  |
Concentration of risk, number of customers | 1 | 1 | 2
Concentration Risk, Percentage | 38.00% | 38.00% | 40.00%
Entity-Wide Revenue, Major Customer, Amount | $ 69.3 | $ 62.9 | $ 109.9
Accounts Receivable [Member] | Customer Concentration Risk [Member] |  |  |
Concentration Risk |  |  |
Concentration Risk, Percentage | 32.00% | 34.00% |

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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13537-108611 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13531-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592 + Details
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- Definition Amount of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 131 -Paragraph 39 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 42 -URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9054-108599 + Details
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