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Share-Based Payments (Details Textual) | 6 Months Ended
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Jun. 30, 2014 | Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Performance multiplier | 0.5 |
Number of days for calculation of average closing stock price | 30 days |
Shares issued under ESPP | 112,000 | 160,000
Market stock units |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Number of equal annual increments | 3 |
Minimum target number of market stock units granted based on stock performance in percent | 0.00% |
Maximum target number of market stock units granted based on stock performance in percent | 200.00% |
Performance units |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Number of equal annual increments | 3 |
Minimum target number of market stock units granted based on stock performance in percent | 0.00% |
Maximum target number of market stock units granted based on stock performance in percent | 200.00% |

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- Definition Number of shares issued during the period as a result of an employee stock purchase plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 + Details
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