Materials, Supplies, and Inventories (Tables)

9 Months Ended

Sep. 30, 2016

Inventory Disclosure [Abstract]

Schedule of inventory

Our inventory consisted of:

(in millions)	September 30, 2016		December 31, 2015
Natural gas in storage	$	298.5	$	284.1
Materials and supplies	209.3		219.2
Fossil fuel	146.5		183.7
Total	$	654.3	$	687.0