ARO Trust (Tables)

3 Months Ended

Mar. 31, 2020

Investments, Debt and Equity Securities [Abstract]

ARO Trust

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

	March 31, 2020				December 31, 2019
	Amortized Cost Basis		Fair Value		Amortized Cost Basis		Fair Value
Money Market Funds	$	22.4	$	22.4	$	15.8	$	15.8
U.S. Equity Funds	63.3		74.5		55.3		83.3
International Equity Funds	36.8		32.3		31.8		35.4
Municipal Bond Funds	58.2		59.0		64.7		66.1
Total	$	180.7	$	188.2	$	167.6	$	200.6