Basis of Presentation and Significant Accounting Policies (Summary of Net Operating Revenues by Payor Source) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 442,805	$ 486,820
Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	100.00%	100.00%
Medicare [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 129,046	$ 144,583
Medicare [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	29.10%	29.70%
Medicaid [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 81,924	$ 85,103
Medicaid [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	18.50%	17.50%
Managed Care and Commercial Plans [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 174,075	$ 185,226
Managed Care and Commercial Plans [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	39.30%	38.00%
Self-Pay and Self-Pay After Insurance [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 37,137	$ 49,684
Self-Pay and Self-Pay After Insurance [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	8.40%	10.20%
Non-Patient [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 20,623	$ 22,224
Non-Patient [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	4.70%	4.60%