Investment in Unconsolidated Affiliates Summarized Balance Sheet Information of Equity Method Investment (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Summarized Balance Sheet Information of Equity Method Investment [Abstract]
Current assets	$ 446.0	$ 396.0
Non-current assets	10,816.0	10,816.0
Current liabilities	831.0	362.0
Non-current liabilities	$ 2,740.0	$ 3,056.0

Summarized Balance Sheet Information of Equity Method Investment [Abstract]

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The amount of current assets reported by an equity method investment of the entity.

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