Basis of Presentation and Significant Accounting Policies (Summary of Net Operating Revenues by Payor Source) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 442,170	$ 472,632	$ 884,975	$ 959,452
Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Medicare [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 119,885	$ 130,106	$ 248,931	$ 274,689
Medicare [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	27.10%	27.50%	28.10%	28.60%
Medicaid [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 96,794	$ 87,141	$ 178,718	$ 172,244
Medicaid [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	21.90%	18.40%	20.20%	18.00%
Managed Care and Commercial Plans [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 174,658	$ 189,726	$ 348,733	$ 374,952
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	39.50%	40.30%	39.40%	39.00%
Self-Pay and Self-Pay After Insurance [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 32,534	$ 42,288	$ 69,671	$ 91,972
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	7.40%	8.90%	7.90%	9.60%
Non-Patient [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Net operating revenues	$ 18,299	$ 23,371	$ 38,922	$ 45,595
Non-Patient [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	4.10%	4.90%	4.40%	4.80%