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Share-Based Payments (Details 9) (USD $) In Millions, except Share data, unless otherwise specified | 12 Months Ended
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Shares issued under employee stock purchase plan |  |  |
Shares issued under ESPP | 245,000 | 274,000 | 434,000
Cash received under ESPP | $ 38.7 | $ 28.7 | $ 22.8

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