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Fair Value Measurements Fair Value Measurements, Narrative (Details) - USD ($) $ / shares in Units, $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2015 | Dec. 31, 2013 | Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items] |  |  |
Fair Value, Net Asset (Liability) | $ (14.6) |  | $ (11.1)
(Decrease)/increase in diluted earnings per share resulting from adjustment |  | $ (0.00) |
Weighted-average credit-adjusted risk-free rate | 8.70% |  |
Minimum |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Short Term Investment Maturity Period | 1 month |  |
Maximum |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Short Term Investment Maturity Period | 3 months |  |

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