SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Buildings and improvements | Minimum
Property and equipment
Useful life	15 years
Buildings and improvements | Maximum
Property and equipment
Useful life	40 years
Equipment | Minimum
Property and equipment
Useful life	3 years
Equipment | Maximum
Property and equipment
Useful life	15 years
Newly constructed hospitals
Property and equipment
Useful life	50 years
Construction in progress
Property and equipment
Interest costs capitalized related to construction projects	$ 22	$ 12	$ 25