Summary of Significant Accounting Policies Leases (Details) $ in Millions	1 Months Ended
	Jan. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jan. 01, 2019 USD ($) land_easement
Lessee, Lease, Description [Line Items]
Operating lease right of use assets		$ 20.7	$ 41.4
Total Liabilities
Lessee, Lease, Description [Line Items]
Operating lease liabilities		$ 35.8
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Impairment losses recorded upon adoption of ASU 2016-02	$ 0.0
Finance lease expense impact of adoption of ASU 2016-02	$ 0.0
Accounting Standards Update 2016-02 | Total Assets
Lessee, Lease, Description [Line Items]
Operating lease right of use assets				$ 49.0
Accounting Standards Update 2016-02 | Total Liabilities
Lessee, Lease, Description [Line Items]
Operating lease liabilities				$ 48.8
Accounting Standards Update 2018-01
Lessee, Lease, Description [Line Items]
Number of land easements treated as leases upon adoption of ASU 2016-02 | land_easement				0