Commitments and Contingencies, Variable Interest Entities (Details) - Low-Income Housing Limited Partnerships - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Amount Reflected in Consolidated Balance Sheets [Abstract]
Current assets	$ 0.3	$ 0.3
Property, plant and equipment, net	0.9	0.9
Other noncurrent assets	0.1	0.1
Total assets	1.3	1.3
Current liabilities	0.0	0.0
Mortgages and other long-term debt payable	0.5	0.5
Other noncurrent liabilities	0.0	0.0
Total liabilities	$ 0.5	$ 0.5