Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2018
ASCO Customer Relationships
Goodwill And Intangible Assets [Line Items]
Finite-Lived Assets, Weighted Average Amortization Period		15 years	10 years
Goodwill
Goodwill And Intangible Assets [Line Items]
Increase (decrease) in fair value of identifiable intangible assets and goodwill	$ 1.4
Finite-Lived Intangible Assets
Goodwill And Intangible Assets [Line Items]
Increase (decrease) in fair value of identifiable intangible assets and goodwill	$ (1.4)