Commitments and Contingencies (Narrative) (Details) $ in Thousands		9 Months Ended
	Apr. 05, 2019 USD ($)	Sep. 30, 2019 USD ($) $ / Person	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Commitments and Contingencies [Line Items]
Self-insured health insurance, liability		$ 304	$ 232
Derivative Liability		10,544	24,976	$ 37,096
Derivative Financial Instrument, Liabilities, Fair Value Disclosure, Noncurrent		9,290	11,209
Derivative Financial Instrument, Liabilities, Fair Value Disclosure, Current		$ 1,254	13,767
Maximum [Member]
Commitments and Contingencies [Line Items]
Self-insured health insurance limit, per person | $ / Person		120,000
Self-insured health Insurance, aggregate liability based on participants and claims (percentage)		125.00%
Self-insured health insurance, estimated cumulative liability for annual contract		$ 3,300
Contingent Accrued Earn-out Acquisition Consideration [Member]
Commitments and Contingencies [Line Items]
Derivative Liability		10,500	25,000
Contingent liability for accrued earn-out acquisition consideration		9,300	11,200
Business Combination, Contingent Consideration, Liability, Current		$ 1,300	$ 13,800
Settled Litigation [Member]
Commitments and Contingencies [Line Items]
Loss Contingency, Damages Sought, Legal Expenses, Value	$ 19,650