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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Total net operating revenues, before the provision for bad debts	$ 585,215	$ 598,163	$ 1,173,160	$ 1,212,647
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]
Total net operating revenues, before the provision for bad debts	$ 160,167	$ 167,549	$ 335,460	$ 343,083
Medicare [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	27.40%	28.00%	28.60%	28.30%
Medicaid [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Total net operating revenues, before the provision for bad debts	$ 107,341	$ 113,283	$ 204,010	$ 216,351
Medicaid [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	18.30%	18.90%	17.40%	17.80%
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	$ 238,448	$ 230,595	$ 470,005	$ 474,879
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	40.70%	38.60%	40.00%	39.20%
Self-Pay [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Total net operating revenues, before the provision for bad debts	$ 55,310	$ 59,171	$ 114,390	$ 123,925
Self-Pay [Member] | Sales Revenue, Net [Member] | Payor Concentration Risk [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Concentration risk, percentage	9.50%	9.90%	9.80%	10.20%
Non-Patient [Member]
Health Care Organization Receivable And Revenue Disclosures [Line Items]
Total net operating revenues, before the provision for bad debts	$ 23,949	$ 27,565	$ 49,295	$ 54,409
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%	4.60%	4.20%	4.50%