Carryforwards (Details 5) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
State and local jurisdiction [Member]
Carryforwards [Line Items]
Operating loss carryforwards	$ 153.2	$ 130.1
Investment tax credit carryforward, amount	32.2	28.0
Federal and State Taxing Authority [Member]
Carryforwards [Line Items]
Tax credit carryforward, amount	$ 43.5	$ 52.5