EQUITY - NARRATIVE (Details) - USD ($)		1 Months Ended	6 Months Ended		12 Months Ended
	Feb. 15, 2018	Mar. 31, 2015	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Mar. 31, 2011
Class of Stock [Line Items]
Proceeds from stock options and ESPP			$ 40,200,000	$ 82,600,000
Common stock repurchased under Buyback			$ 100,000,000	$ 641,400,000
Shares repurchased, as of (in shares)			9,631,000		8,909,000
Stock repurchased, as of			$ 1,074,000,000		$ 974,000,000
Accrued dividend RSU			9,900,000
Dividends Declared and Paid
Class of Stock [Line Items]
Paid dividend RSU			$ 4,200,000
2011 Buyback
Class of Stock [Line Items]
Stock repurchase program, authorized amount						$ 1,500,000,000.0
Stock repurchased under Buyback (in shares)			722,032
Common stock repurchased under Buyback			$ 100,000,000
Accrued treasury stock purchases			$ 1,400,000
Shares repurchased, as of (in shares)			13,078,086
Stock repurchased, as of			$ 1,300,000,000
2017 Buyback
Class of Stock [Line Items]
Stock repurchase program, authorized amount					$ 2,000,000,000.0
Common stock repurchased under Buyback			$ 0
Preferred Stock - Series B
Class of Stock [Line Items]
Depository shares, percentage of preferred shares (in shares)			0.1
Convertible Preferred Stock Subject to Mandatory Redemption
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)			$ 0.01		$ 0.01
Convertible Preferred Stock Subject to Mandatory Redemption | Preferred Stock - Series B
Class of Stock [Line Items]
Preferred stock, dividend rate percentage (in percent)			5.50%		5.50%
Convertible Preferred Stock Subject to Mandatory Redemption | Preferred Stock - Series B | Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)		1,375,000
Preferred stock, dividend rate percentage (in percent)		5.50%
Preferred stock, par value (in dollars per share)		$ 0.01
Conversion factor, preferred stock (in shares)			8.7420
Conversion factor, depository shares, preferred stock			0.8742
Conversion of preferred stock (shares)		12,020,064	(1,375,000)	0
Dividends paid to holder of Series B Preferred Stock	$ 18,900,000