SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary of Significant Accounting Policies [Line Items]
Equity method investments carrying value	$ 443				$ 473				$ 443	$ 473
Share of equity earnings from investments in affiliates									$ 39	$ 23	$ 26
Percentage of total revenues generated by medicaid and medicare programs									17.00%	17.00%	17.00%
Purchase price discount ESPP	15.00%								15.00%
Percentage of accounts receivable due from government payers	15.00%				16.00%				15.00%	16.00%
Percentage of receivables due from patients	17.00%				17.00%				17.00%	17.00%
Net income	$ 167	$ 205	$ 209	$ 115	$ 200	$ 354	$ 129	$ 70	$ 696	$ 753	$ 592
Available-for-sale equity securities	3				6				3	6
Trading equity securities	51				49				51	49
Other investments	6				8				6	8
Total	60				$ 63				60	63
Gross unrealized gains from available-for-sale equity securities	$ 5								5
Trading equity securities gain or (loss)									3	0	3
Net cash provided by (used in) operating activities									1,069	821	944
Net cash (used in) provided by financing activities									(691)	(518)	86
Operating income (loss)									1,277	1,399	983
Service Life [Member]
Summary of Significant Accounting Policies [Line Items]
Net income									$ 23
Earnings per share, basic and diluted									$ 0.16
Operating income (loss)									$ 37
New Accounting Pronouncement, Early Adoption, Effect [Member] | Accounting Standards Update 2016-09, Excess Tax Benefit Component [Member]
Summary of Significant Accounting Policies [Line Items]
Effect of adoption, quantification									$ 9
Net cash provided by (used in) operating activities										5	0
Net cash (used in) provided by financing activities										5	0
New Accounting Pronouncement, Early Adoption, Effect [Member] | Accounting Standards Update 2016-09, Taxes Paid Related to Employee Payroll [Member]
Summary of Significant Accounting Policies [Line Items]
Net cash provided by (used in) operating activities										7	6
Net cash (used in) provided by financing activities										$ 7	$ 6
Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage	20.00%								20.00%
Finite-lived intangible asset, useful life									5 years
Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage	49.00%								49.00%
Finite-lived intangible asset, useful life									20 years
Building and Building Improvements [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									31 years 6 months
Laboratory Equipment and Furniture and Fixtures [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									5 years
Laboratory Equipment and Furniture and Fixtures [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									12 years
Internal Use Software [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									5 years
Laboratory Equipment [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									7 years	5 years
Laboratory Equipment [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									10 years	7 years
Furniture and Fixtures [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									5 years	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									12 years	7 years
Software and Software Development Costs [Member]
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life									5 years	3 years