Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Unfunded credit commitments liability	$ 1.9	$ 1.9
Fair value of interest rate swap assets	60.6	22.5
Fair value of interest rate swap liabilities	59.7	22.2
Lessee, Lease, Description [Line Items]
Total operating rental expense	6.2
Total rental expense		5.8	$ 5.5
Rental income	$ 0.4	$ 0.4	$ 0.4
Minimum
Lessee, Lease, Description [Line Items]
Term of operating lease	3 years
Maximum
Lessee, Lease, Description [Line Items]
Term of operating lease	25 years