Summary of Significant Accounting Policies - High Deductible Insurance (Details) $ in Millions	Dec. 31, 2018 USD ($)
Workers' Compensation [Member]
Insurance coverage [Line Items]
Maximum Retention	$ 0.8
Minimum [Member] | General Liability [Member]
Insurance coverage [Line Items]
Maximum Retention	0.3
Maximum [Member] | General Liability [Member]
Insurance coverage [Line Items]
Maximum Retention	1.5
Maximum [Member] | Group Medical Plan [Member]
Insurance coverage [Line Items]
Stop Loss Limit	$ 0.3