New Accounting Pronouncements - Additional Information (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement
Accumulated Other Comprehensive Loss	$ (242.5)	$ (814.2)
Retained Earnings	10,308.9	9,863.1
Other Long-term Investments	735.0	702.9
Deferred Income Tax	$ 37.0	$ 0.0
Accounting Standards Update 2016-01 \| Effect of Change
Error Corrections and Prior Period Adjustments Restatement
Accumulated Other Comprehensive Loss			$ (17.5)
Retained Earnings			14.5
Other Long-term Investments			(3.8)
Deferred Income Tax			$ (0.8)

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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