STOCKHOLDERS' EQUITY - Capital Stock (Details) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) $ / shares shares
Equity [Abstract]
Equity Offering Program, Authorized Offering Amount	$ 1,000.0
Stock Issued During Period, Shares, New Issues, Equity Offering Program | shares	1.6
Stock issued during period, gross proceeds per share, equity offering program | $ / shares	$ 64.15
Stock Issued During Period, Value, New Issues, Equity Offering Program	$ 98.5
Equity offering program, remaining authorized offering amount	$ 900.0