Carryforwards (Details 5) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
State and local jurisdiction
Carryforwards [Line Items]
Operating loss carryforwards	$ 149.8	$ 153.2
Investment tax credit carryforward, amount	37.4	32.2
Federal and State Taxing Authority
Carryforwards [Line Items]
Tax credit carryforward, amount	$ 43.7	$ 43.5