Basis of Presentation and Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 segment item state	Dec. 31, 2011	Dec. 31, 2010
Business Description [Abstract]
Number of hospitals owned or leased by the Company	135
Number of stand alone rehabilitation or psychiatric hospitals	4
Number of licensed beds	20,334
Number of states in which we operate	29
Cost of Revenue, Policy [Abstract]
Operating costs and expenses, corporate office costs	$ 214,800,000	$ 183,400,000	$ 155,400,000
Stock-based compensation expense	40,896,000	42,542,000	38,779,000
Marketable Securities, Policy [Abstract]
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	4,588,000	1,576,000	2,536,000
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	3,012,000	(960,000)	3,716,000
Property and Equipment, Policy [Abstract]
Construction in Progress, Gross	173,400,000	397,200,000
Interest Costs Capitalized	23,900,000	21,400,000	11,900,000
Purchases of property and equipment accrued in accounts payable	50,200,000	94,200,000
Third Party Reimbursement, Policy [Abstract]
Percentage of net operating revenues related to services rendered to patients covered by the Medicare and Medicaid programs	36.10%	36.50%	38.10%
Percentage of revenues from Medicare outlier payments included in amounts received from Medicare	0.45%	0.42%	0.43%
Reimbursement Settlement and Payment Included in Net Operating Revenues	105,300,000
Unfavorable Adjustment Related To the Revised Supplemental Security Income Ratios Utilized for Calculating Medicare Disportionate Share Hospital Reimbursements	21,000,000
Amounts due to third party payors	80,500,000	66,000,000
Amounts due from third party payors	119,200,000	86,500,000
Net Operating Revenues, Policy [Abstract]
Provision for contractual allowance included in net operating revenues	49,300,000,000	42,400,000,000	35,800,000,000
Value of administrative and other discounts provided to self-pay patients included in contractual allowances	1,200,000,000	852,400,000	689,400,000
Value of charity care services at the Company's standard charges included in contractual allowances	692,400,000	651,100,000	512,400,000
Estimated cost incurred by Company to provide charity care services	125,400,000	125,700,000	105,500,000
Allowance for Doubtful Accounts, Policy [Abstract]
Percentage reserved for all non-self-pay payors accounts aging over 365 days from the date of discharge	100.00%
Number of days from the date of discharge over which all accounts are reserved 100%	365 days
Electronic Health Records Reimbursement, Policy [Abstract]
Electronic health records incentive reimbursement under HITECH	126,734,000	63,397,000
Electronic Health Records Incentive Reimbursement, Cash Received	141,000,000	37,400,000
Electronic Health Records Incentive Reimbursement, Deferred Revenue	33,300,000	8,500,000
Physician Income Guarantees, Policy [Abstract]
Finite-Lived Intangible Assets, Net	26,300,000	30,600,000
Concentration of Credit Risk, Policy [Abstract]
Accounts receivable, net of contractual allowances, from Medicare	2,067,379,000	1,834,167,000
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment of long-lived assets	10,000,000
Segment Reporting, Policy [Abstract]
Number of Operating Segments	3
Geographic Concentration Risk [Member] | Indiana [Member]
Business Description [Abstract]
Operating revenues, net of contractual allowances and discounts (but before the provision for bad debts) as a percentage of consolidated operating revenues	10.50%	10.30%	10.60%
Geographic Concentration Risk [Member] | Texas [Member]
Business Description [Abstract]
Operating revenues, net of contractual allowances and discounts (but before the provision for bad debts) as a percentage of consolidated operating revenues	14.40%	13.10%	13.00%
Geographic Concentration Risk [Member] | Pennsylvania [Member]
Business Description [Abstract]
Operating revenues, net of contractual allowances and discounts (but before the provision for bad debts) as a percentage of consolidated operating revenues	12.60%	11.50%	10.30%
Capitalized Internal Use Software, Except Significant System Conversions [Member]
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life	3 years
Finite-Lived Intangible Assets, Except Capitalized Internal-Use Software [Member]
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life	8 years
Physician recruitment contracts [Member]
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life	3 years
Physician Income Guarantees, Policy [Abstract]
Physicians recruitment agreement period	1 year
Term of Physician Recruitment Contract	3 years
Finite-Lived Intangible Assets, Net	30,100,000	33,000,000
Maximum [Member] | Land Improvements [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life	15 years
Maximum [Member] | Building and Building Improvements [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life	50 years
Maximum [Member] | Furniture and Fixtures [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life	18 years
Maximum [Member] | Capitalized Internal Use Software, Significant System Conversions [Member]
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life	10 years
Minimum [Member] | Land Improvements [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life	2 years
Minimum [Member] | Building and Building Improvements [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life	5 years
Minimum [Member] | Furniture and Fixtures [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life	4 years
Minimum [Member] | Capitalized Internal Use Software, Significant System Conversions [Member]
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life	8 years
Weighted Average [Member] | Land Improvements [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life	14 years
Weighted Average [Member] | Building and Building Improvements [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life	24 years
Weighted Average [Member] | Furniture and Fixtures [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life	8 years
Medicare [Member]
Concentration of Credit Risk, Policy [Abstract]
Accounts receivable, net of contractual allowances, from Medicare	$ 315,500,000	$ 250,800,000
Accounts receivable, net of contractual allowances, from Medicare as a percentage of consolidated net accounts receivable, before allowance for doubtful accounts	7.40%	6.70%