ARO Trust (Tables)

9 Months Ended

Sep. 30, 2019

Investments, Debt and Equity Securities [Abstract]

ARO Trust

Investments within the ARO Trust at fair value were as follows (in millions): 

	September 30, 2019				December 31, 2018
	Amortized Cost Basis		Fair Value		Amortized Cost Basis		Fair Value
Money Market Funds	$	23.3	$	23.3	$	21.7	$	21.7
U.S. Equity Funds	54.7		76.2		46.4		56.8
International Equity Funds	25.4		27.0		21.9		21.4
Municipal Bond Funds	59.3		60.8		50.1		49.6
Total	$	162.7	$	187.3	$	140.1	$	149.5