Basis of Presentation and Significant Accounting Policies (Summary of Net Operating Revenues, Before the Provision for Bad Debts, by Payor Source) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Total net operating revenues, before the provision for bad debts	$ 587,945	$ 614,484
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]
Total net operating revenues, before the provision for bad debts	$ 175,293	$ 175,534
Medicare [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	29.80%	28.60%
Medicaid [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Total net operating revenues, before the provision for bad debts	$ 96,669	$ 103,068
Medicaid [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	16.40%	16.80%
Managed Care and Commercial Plans [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Total net operating revenues, before the provision for bad debts	$ 231,557	$ 244,284
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	39.40%	39.80%
Self-Pay [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Total net operating revenues, before the provision for bad debts	$ 59,080	$ 64,754
Self-Pay [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	10.00%	10.50%
Non-Patient [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Total net operating revenues, before the provision for bad debts	$ 25,346	$ 26,844
Non-Patient [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	4.40%	4.30%