Equity Investments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 504		$ 479
Equity in earnings of unconsolidated affiliates	$ 20	$ 18
Four Hospitals in Las Vegas, Nevada [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	27.50%
One Hospital in Las Vegas, Nevada [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	26.10%
Three Hospitals in Macon Georgia, [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	38.00%
HealthTrust [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	24.70%