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Fair Value - Recurring Fair Value Measures (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2019 | Dec. 31, 2018
Investments [Abstract] |  |  |  |
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value |  | $ 1.7 |  |
Available-for-sale Securities, Debt Maturities, After One Year Through Three Years, Fair Value |  | 4.0 |  |
Available-for-sale Securities, Debt Maturities, After Three Years Through Five Years, Fair Value |  | 1.8 |  |
Available-for-sale Securities, Debt Maturities, After Five Years, Fair Value |  | 0.8 |  |
Recurring Fair Value Measures [Member] |  |  |  |
Investments [Abstract] |  |  |  |
Available-for-sale – Equity Securities | [1] | 12.3 |  | $ 12.2
Available-for-sale – Corporate and Governmental Debt Securities (b) | [1] | 8.3 | [2] | 8.0
Cash Equivalents | [1] | 1.0 |  | 1.0
Total Fair Value of Assets |  | 21.6 |  | 21.2
Liabilities [Abstract] |  |  |  |
Deferred Compensation | [3] | 21.6 |  | 19.8
U.S. Water Services Contingent Consideration |  |  |  | 3.8
Total Fair Value of Liabilities |  | 21.6 |  | 23.6
Total Net Fair Value of Assets (Liabilities) |  | 0.0 |  | (2.4)
Recurring Fair Value Measures [Member] | Level 1 [Member] |  |  |  |
Investments [Abstract] |  |  |  |
Available-for-sale – Equity Securities | [1] | 12.3 |  | 12.2
Available-for-sale – Corporate and Governmental Debt Securities (b) | [1] | 0.0 | [2] | 0.0
Cash Equivalents | [1] | 1.0 |  | 1.0
Total Fair Value of Assets |  | 13.3 |  | 13.2
Liabilities [Abstract] |  |  |  |
Deferred Compensation | [3] | 0.0 |  | 0.0
U.S. Water Services Contingent Consideration |  |  |  | 0.0
Total Fair Value of Liabilities |  | 0.0 |  | 0.0
Total Net Fair Value of Assets (Liabilities) |  | 13.3 |  | 13.2
Recurring Fair Value Measures [Member] | Level 2 [Member] |  |  |  |
Investments [Abstract] |  |  |  |
Available-for-sale – Equity Securities | [1] | 0.0 |  | 0.0
Available-for-sale – Corporate and Governmental Debt Securities (b) | [1] | 8.3 | [2] | 8.0
Cash Equivalents | [1] | 0.0 |  | 0.0
Total Fair Value of Assets |  | 8.3 |  | 8.0
Liabilities [Abstract] |  |  |  |
Deferred Compensation | [3] | 21.6 |  | 19.8
U.S. Water Services Contingent Consideration |  |  |  | 0.0
Total Fair Value of Liabilities |  | 21.6 |  | 19.8
Total Net Fair Value of Assets (Liabilities) |  | (13.3) |  | (11.8)
Recurring Fair Value Measures [Member] | Level 3 [Member] |  |  |  |
Investments [Abstract] |  |  |  |
Available-for-sale – Equity Securities | [1] | 0.0 |  | 0.0
Available-for-sale – Corporate and Governmental Debt Securities (b) | [1] | 0.0 | [2] | 0.0
Cash Equivalents | [1] | 0.0 |  | 0.0
Total Fair Value of Assets |  | 0.0 |  | 0.0
Liabilities [Abstract] |  |  |  |
Deferred Compensation | [3] | 0.0 |  | 0.0
U.S. Water Services Contingent Consideration |  |  |  | 3.8
Total Fair Value of Liabilities |  | 0.0 |  | 3.8
Total Net Fair Value of Assets (Liabilities) |  | 0.0 |  | $ (3.8)
Recurring Fair Value Measures [Member] | Level 3 [Member] | Payments [Member] |  |  |  |
Liabilities [Abstract] |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Period Increase (Decrease) |  | $ 3.8 |  |
[1] | Included in Other Investments on the Consolidated Balance Sheet.
[2] | As of March 31, 2019, the aggregate amount of available-for-sale corporate and governmental debt securities maturing in one year or less was $1.7 million, in one year to less than three years was $4.0 million, in three years to less than five years was $1.8 million and in five or more years was $0.8 million.
[3] | Included in Other Non-Current Liabilities on the Consolidated Balance Sheet.

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