Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Condensed Consolidated Balance Sheets [Abstract]
Allowance for doubtful patient accounts	$ 3,628	$ 3,504
Other current assets of hospitals held for sale	7	38
Noncurrent assets of hospitals held for sale	36	90
Current liabilities of hospitals held for sale	$ 2	$ 10
Preferred stock, par value per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000,000us-gaap_PreferredStockSharesAuthorized	100,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	300,000,000us-gaap_CommonStockSharesAuthorized	300,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	119,000,326us-gaap_CommonStockSharesIssued	117,701,087us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	118,024,777us-gaap_CommonStockSharesOutstanding	116,725,538us-gaap_CommonStockSharesOutstanding
Treasury stock, shares	975,549us-gaap_TreasuryStockShares	975,549us-gaap_TreasuryStockShares

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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