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Summary of Significant Accounting Policies Awards Outstanding (Details) - shares | Jun. 30, 2015 | Dec. 31, 2014
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Stock options |  |
Awards outstanding [Line Items] |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 867,877 | 961,377
Restricted Stock Units (RSUs) [Member] |  |
Awards outstanding [Line Items] |  |
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number | 2,103,751 | 1,830,291
Performance Shares [Member] |  |
Awards outstanding [Line Items] |  |
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number | 32,000 | 34,000
Stock appreciation rights |  |
Awards outstanding [Line Items] |  |
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number | 605,692 | 673,068
Market share units |  |
Awards outstanding [Line Items] |  |
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number | 563,300 | 444,272

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- Definition Number of equity instruments other than options outstanding, including both vested and non-vested instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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