Commitments and Contingencies Concentrations (Details) - Total Medicaid and Medicare	12 Months Ended
	Dec. 31, 2018 Rate	Dec. 31, 2017 Rate	Dec. 31, 2016 Rate
Concentration Risk [Line Items]
Accounts receivable by payor as a percent of total accounts receivable	60.60%	56.70%
% of Revenue	68.50%	68.40%	67.80%