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Operations and Significant Accounting Policies - New Accounting Pronouncements (Details) $ in Millions | 9 Months Ended
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Sep. 30, 2017 USD ($)
Improvements to Employee Share-Based Payment Accounting [Member] | Income Tax Expense (Benefit) [Member] | Maximum [Member] |
New Accounting Pronouncements [Line Items] |
Impact of Adoption Annually | $ 1

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