Fair Value (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Recurring Fair Value Measures [Table Text Block]

	Fair Value as of December 31, 2017
Recurring Fair Value Measures	Level 1		Level 2		Level 3		Total
Millions
Assets:
Investments (a)
Available-for-sale – Equity Securities		$10.2	—		—			$10.2
Available-for-sale – Corporate and Governmental Debt Securities	—			$8.9	—		8.9
Cash Equivalents	3.8		—		—		3.8
Total Fair Value of Assets		$14.0		$8.9	—			$22.9
Liabilities: (b)
Deferred Compensation	—			$18.2	—			$18.2
U.S. Water Services Contingent Consideration	—		—			$5.4	5.4
Total Fair Value of Liabilities	—			$18.2		$5.4		$23.6
Total Net Fair Value of Assets (Liabilities)		$14.0	$(9.3)		$(5.4)		$(0.7)

(a) Included in Other Investments on the Consolidated Balance Sheet.

(b) Included in Other Non-Current Liabilities on the Consolidated Balance Sheet.

	Fair Value as of December 31, 2018
Recurring Fair Value Measures	Level 1		Level 2		Level 3		Total
Millions
Assets:
Investments (a)
Available-for-sale – Equity Securities		$12.2	—		—			$12.2
Available-for-sale – Corporate and Governmental Debt Securities	—			$8.0	—		8.0
Cash Equivalents	1.0		—		—		1.0
Total Fair Value of Assets		$13.2		$8.0	—			$21.2
Liabilities:
Deferred Compensation (b)	—			$19.8	—			$19.8
U.S. Water Services Contingent Consideration (c)	—		—			$3.8	3.8
Total Fair Value of Liabilities	—			$19.8		$3.8		$23.6
Total Net Fair Value of Assets (Liabilities)		$13.2	$(11.8)		$(3.8)		$(2.4)

(a) Included in Other Investments on the Consolidated Balance Sheet.

(b) Included in Other Non-Current Liabilities on the Consolidated Balance Sheet.

(c) Included in Other Current Liabilities on the Consolidated Balance Sheet.

Recurring Fair Value Measures - Activity in Level 3 [Table Text Block]

Recurring Fair Value Measures
Activity in Level 3
Millions
Balance as of December 31, 2016		$25.0
Accretion (a)	0.8
Payments (b)	(19.7		)
Changes in Cash Flow Projections	(0.7		)
Balance as of December 31, 2017		$5.4
Accretion (a)	0.4
Changes in Cash Flow Projections	(2.0		)
Balance as of December 31, 2018		$3.8

(a) Included in Interest Expense on the Consolidated Statement of Income.

(b) Payments reflect the impact of a modification to the shareholder agreement in the first quarter of 2017 which provided participants a one-time election to sell shares at a determined price. Participants representing approximately half of the outstanding contingent consideration shares made the election, and were paid in 2017.

Financial Instruments [Table Text Block]

Financial Instruments	Carrying Amount	Fair Value
Millions
Long-Term Debt, Including Long-Term Debt Due Within One Year
December 31, 2018	$1,495.2	$1,534.6
December 31, 2017	$1,513.3	$1,627.6