Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Non-cash goodwill and impairment charge	$ 82.2
Amortization of intangible assets	0.3	$ 0.8	$ 3.0
Future amortization expense, 2019	0.3
Future amortization expense, 2020	0.3
Future amortization expense, 2021	0.3
Future amortization expense, 2022	$ 0.3