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Interim Financial Statements (Recent Accounting Pronouncements) (Details) $ in Millions | 6 Months Ended
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Jun. 30, 2017 USD ($)
Accounting Standards Update 2016-09 [Member] |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |
Income tax deficiency from stock-based awards | $ 1.8
Cumulative effect on retained earnings (pre-tax), share-based accounting standard | 0.2
Accounting Standards Update 2016-02 [Member] | Minimum [Member] |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |
Expected additional operating lease liability | 300.0
Accounting Standards Update 2016-02 [Member] | Maximum [Member] |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |
Expected additional operating lease liability | $ 400.0

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