Supplemental Financial Information (Other Assets, Net) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Supplemental Financial Information [Abstract]
Operating Lease, Right-of-Use Asset	$ 57.1	$ 0.0
Deferred tax assets	31.4	29.4
Supplemental executive retirement plan assets	26.2	27.2
Deferred costs	19.9	21.5
Intangible Assets, Net (Excluding Goodwill)	14.9	0.0
Other	19.9	19.7
Other assets, net	$ 169.4	$ 97.8

The amount of cash, securities, or other assets held by a third-party trustee pursuant to the terms of an agreement which assets are available to be used by beneficiaries to that agreement only within the specific terms thereof and which agreement is expected to terminate more than one year from the balance sheet date (or operating cycle, if longer) at which time the assets held-in-trust will be released or forfeited.

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Amount of deferred cost, excluding capitalized cost related to contract with customer; classified as noncurrent.

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Amount of lessee's right to use underlying asset under operating lease.

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