Basis of Presentation and Significant Accounting Policies (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Revenues and Accounts Receivable [Abstract]
Increase (decrease) in net operating revenues during period for contractual adjustments related to final cost report settlements on previous program reimbursements	$ (2,500,000)	$ (11,200,000)	$ (4,400,000)	$ (11,700,000)
Operating revenues	3,042,786,000	2,923,172,000	6,123,439,000	5,771,609,000
Charity care costs	1,200,000	1,100,000	2,400,000	2,300,000
Concentration of Credit Risk [Abstract]
Accounts receivable, net of contractual allowances	394,120,000		394,120,000		$ 390,890,000
General and Administrative Costs [Abstract]
General and administrative costs	11,700,000	11,100,000	23,700,000	22,100,000
Intangible Assets [Abstract]
Acquired finite-lived intangible asset, residual value	0		0
Self-Insured Medical Benefits [Abstract]
Undiscounted reserve for self-insured employee health benefits	12,400,000		$ 12,400,000
Restricted Stock [Member]
Stock-Based Compensation [Abstract]
Shares distributed to each stockholder in spin off transaction for every four shares held			1
Shares held by each stockholder of parent used to receive one share distribution in spin off transaction			4
Capitalized Internal Use Software, Except Significant System Conversions [Member]
Intangible Assets [Abstract]
Finite-lived intangible assets, useful life			3 years
Accounts Receivable [Member] | Credit Concentration Risk [Member]
Concentration of Credit Risk [Abstract]
Concentration risk, percentage			100.00%		100.00%
Minimum [Member]
Revenues and Accounts Receivable [Abstract]
Number of days from date of discharge in which company establishes doubtful accounts reserve on non-self pay payor receivables			365 days
Minimum [Member] | Capitalized Internal Use Software, Significant System Conversions [Member]
Intangible Assets [Abstract]
Finite-lived intangible assets, useful life			8 years
Minimum [Member] | Land Improvements [Member]
Long-Lived Assets [Abstract]
Estimated useful life of asset			3 years
Minimum [Member] | Buildings and Improvements [Member]
Long-Lived Assets [Abstract]
Estimated useful life of asset			5 years
Minimum [Member] | Equipment and Fixtures [Member]
Long-Lived Assets [Abstract]
Estimated useful life of asset			3 years
Maximum [Member] | Capitalized Internal Use Software, Significant System Conversions [Member]
Intangible Assets [Abstract]
Finite-lived intangible assets, useful life			10 years
Maximum [Member] | Land Improvements [Member]
Long-Lived Assets [Abstract]
Estimated useful life of asset			20 years
Maximum [Member] | Buildings and Improvements [Member]
Long-Lived Assets [Abstract]
Estimated useful life of asset			40 years
Maximum [Member] | Equipment and Fixtures [Member]
Long-Lived Assets [Abstract]
Estimated useful life of asset			18 years
Illinois [Member]
Revenues and Accounts Receivable [Abstract]
Increase (decrease) in net operating revenues during period for contractual adjustments related to final cost report settlements on previous program reimbursements		(11,100,000)		(11,100,000)
Operating revenues			$ 399,049,000	405,390,000
Medicare [Member]
Concentration of Credit Risk [Abstract]
Accounts receivable, net of contractual allowances	75,400,000		$ 75,400,000		$ 67,700,000
Medicare [Member] | Accounts Receivable [Member] | Credit Concentration Risk [Member]
Concentration of Credit Risk [Abstract]
Concentration risk, percentage			10.30%		9.20%
Medicare [Member] | Revenues [Member]
Revenues and Accounts Receivable [Abstract]
Prior period reclassification adjustment	43,400,000	35,500,000	$ 85,100,000	72,100,000
Charity Care [Member]
Revenues and Accounts Receivable [Abstract]
Operating revenues	$ 7,000,000	$ 6,300,000	14,800,000	$ 13,300,000
State Supplemental Payment Programs [Member] | Due from Third-Party Payors [Member]
Revenues and Accounts Receivable [Abstract]
Prior period reclassification adjustment			$ 78,100,000		$ 68,000,000