FAIR VALUE MEASUREMENTS (Narrative) (Details) (USD $)			6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Put Option [Member]	Jun. 30, 2013 Call Option [Member]	Jan. 02, 2013 UMass Memorial Medical Center (UMass) [Member]
Business Acquisitions [Line Items]
Percentage of equity interest expected to be divested					18.90%
Vesting period for derivative instrument			2 years	2 years
Fair value of debt	$ 3,800,000,000	$ 3,800,000,000
Amount exceeding or below of carrying value of debt	$ 262,000,000	$ 481,000,000