Right-of-Use Lease Assets and Lease Liabilities (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Leases [Abstract]
Operating lease, right-of-use asset	$ 35.2	$ 35.2
Operating lease, liability	35.2	35.2
Operating lease, expense	$ 2.7	$ 5.3
Operating ease, weighted average discount rate, percent	3.47%	3.47%
Operating lease, weighted average remaining lease term	8 years 11 months 1 day	8 years 11 months 1 day