XML 32 R22.htm IDEA: XBRL DOCUMENT v3.6.0.2
ARO Trust (Tables)
12 Months Ended
Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]  
ARO Trust
Investments in available-for-sale securities within the ARO Trust at fair value were as follows (in millions):
 
 
 
December 31, 2016
 
December 31, 2015
 
 
Amortized
Cost Basis
 
Fair
Value
 
Amortized
Cost Basis
 
Fair
Value
Cash and Money Market Funds
 
$
5.0

 
$
5.0

 
$
3.2

 
$
3.2

U.S. Equity Funds
 
29.4

 
36.5

 
19.2

 
22.9

International Equity Funds
 
19.2

 
18.6

 
16.1

 
15.0

Municipal Bond Funds
 
36.7

 
36.3

 
25.1

 
25.6

Total
 
$
90.3

 
$
96.4

 
$
63.6

 
$
66.7