Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Total accumulated goodwill impairment	$ 35.5	$ 35.5
Amortization expense of intangible assets	16.8	19.8	$ 24.6
Specialty Product
Goodwill [Line Items]
Goodwill, impairment loss	0.0	$ 0.0
Fuel Product
Goodwill [Line Items]
Goodwill, impairment loss	$ 0.0
Dickinson | Specialty Product
Goodwill [Line Items]
Goodwill, impairment loss			$ 0.7