STOCKHOLDERS' EQUITY - Dividends (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Class of Stock [Line Items]
Dividends declared per share of common stock (in usd per share)	$ 0.32	$ 0.22
Common stock dividends declared and paid	149,000,000	108,000,000
Preferred stock dividends declared and paid	15,000,000	7,000,000
Series A Preferred Stock
Class of Stock [Line Items]
Dividends declared per share of preferred stock (in usd per share)	27.50	27.50
Series B Preferred Stock
Class of Stock [Line Items]
Dividends declared per share of preferred stock (in usd per share)	0.00	0.00
Series C Preferred Stock
Class of Stock [Line Items]
Dividends declared per share of preferred stock (in usd per share)	15.94	0.00
Series D Preferred Stock
Class of Stock [Line Items]
Dividends declared per share of preferred stock (in usd per share)	11.82	0.00
Dividends Declared
Class of Stock [Line Items]
Common stock dividends declared and paid	149,000,000	108,000,000
Preferred stock dividends declared and paid	15,000,000	7,000,000
Dividends Declared | Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock dividends declared and paid	7,000,000	7,000,000
Dividends Declared | Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock dividends declared and paid	0	0
Dividends Declared | Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock dividends declared and paid	5,000,000	0
Dividends Declared | Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock dividends declared and paid	3,000,000	0
Dividends Paid
Class of Stock [Line Items]
Common stock dividends declared and paid	149,000,000	108,000,000
Preferred stock dividends declared and paid	15,000,000	0
Dividends Paid | Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock dividends declared and paid	0	0
Dividends Paid | Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock dividends declared and paid	11,000,000	0
Dividends Paid | Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock dividends declared and paid	4,000,000	0
Dividends Paid | Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock dividends declared and paid	$ 0	$ 0