STOCKHOLDERS' EQUITY - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands									3 Months Ended		4 Months Ended	5 Months Ended	6 Months Ended	12 Months Ended
	Dec. 26, 2019	Aug. 02, 2019	Feb. 28, 2019	Nov. 29, 2018	Mar. 26, 2018	Dec. 22, 2017	Aug. 28, 2017	Feb. 22, 2017	Feb. 28, 2019	Mar. 26, 2018	Dec. 31, 2017	Dec. 26, 2019	Aug. 28, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 19, 2020	Jul. 31, 2019	Jul. 30, 2019	Nov. 28, 2018	Dec. 21, 2017	Dec. 14, 2017	Feb. 16, 2017	Feb. 14, 2017
Equity, Class of Treasury Stock [Line Items]
Share repurchase authorization																			$ 3,000,000,000	$ 3,000,000,000.0	$ 3,000,000,000.0	$ 3,000,000,000	$ 2,250,000,000	$ 2,250,000,000
Shares received (in shares)											3,040
Increase in treasury stock from share repurchases											$ 750,000,000			$ 1,070,000,000	$ 1,090,000,000	$ 3,365,000,000
Remaining share repurchase authorization at replacement																			$ 1,030,000,000.00
Common shares acquired in connection with employee stock plans (in shares)														200	400	500
Common shares acquired in connection with employee stock plans, amount														$ 70,000,000	$ 116,000,000	$ 115,000,000
Aggregate statutory capital and surplus in our state regulated insurance subsidiaries														8,000,000,000.0	7,600,000,000
Aggregate minimum regulatory requirements of statutory capital and surplus														5,900,000,000	5,200,000,000
Dividends that may be paid to the parent company without prior approval by state regulatory authorities in 2014														1,000,000,000.0
Dividends that were paid to the parent company without prior approval by state regulatory authorities														$ 1,800,000,000	$ 2,300,000,000	$ 1,400,000,000
February 2017 ASR
Equity, Class of Treasury Stock [Line Items]
Accelerated share repurchase agreement amount																							$ 1,500,000,000
Accelerated share repurchase payment								$ 1,500,000,000
Shares received (in shares)							840	5,830					6,670
Increase in treasury stock from share repurchases								$ 1,200,000,000
Decrease in capital in excess of par value								$ 300,000,000
Average daily volume weighted-average share price of common stock during term of agreement (in USD per share)													$ 224.81
Reclassification from capital in excess of par value to treasury stock							$ 300,000,000
December 2017 ASR
Equity, Class of Treasury Stock [Line Items]
Accelerated share repurchase agreement amount																					$ 1,000,000,000.0
Accelerated share repurchase payment						$ 1,000,000,000.0
Shares received (in shares)					460	3,280				3,740
Increase in treasury stock from share repurchases						$ 800,000,000
Decrease in capital in excess of par value						$ 200,000,000
Average daily volume weighted-average share price of common stock during term of agreement (in USD per share)										$ 267.55
Reclassification from capital in excess of par value to treasury stock					$ 200,000,000
November 2018 ASR
Equity, Class of Treasury Stock [Line Items]
Accelerated share repurchase agreement amount																				$ 750,000,000
Accelerated share repurchase payment				$ 750,000,000
Shares received (in shares)			600	1,940					2,540
Increase in treasury stock from share repurchases				$ 600,000,000
Decrease in capital in excess of par value				$ 150,000,000
Average daily volume weighted-average share price of common stock during term of agreement (in USD per share)									$ 295.15
Reclassification from capital in excess of par value to treasury stock			$ 150,000,000
July 2019 ASR
Equity, Class of Treasury Stock [Line Items]
Accelerated share repurchase agreement amount																		$ 1,000,000,000
Accelerated share repurchase payment		$ 1,000,000,000
Shares received (in shares)	700	2,700										3,400
Increase in treasury stock from share repurchases		$ 800,000,000
Decrease in capital in excess of par value		$ 200,000,000
Average daily volume weighted-average share price of common stock during term of agreement (in USD per share)												$ 296.19
Reclassification from capital in excess of par value to treasury stock	$ 200,000,000
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Remaining authorized amount																	$ 2,000,000,000.0