SUBSEQUENT EVENTS (Details) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended	6 Months Ended			18 Months Ended
	Jul. 13, 2018	Mar. 08, 2018	Jan. 09, 2018	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	[1]	Dec. 31, 2019	Jul. 10, 2018
Subsequent Event [Line Items]
Proceeds from issuance of shares					$ 2,090.0	$ 28.0
Proceeds from issuance					$ 1,693.0	$ 0.0
Common Stock [Member]
Subsequent Event [Line Items]
Shares issued		8,556,630	26,869,158	7,651,671	16,208,301
Common Stock [Member] | Public Offering [Member]
Subsequent Event [Line Items]
Shares issued			23,364,486
Price of shares issued (in dollars per share)			$ 107.00
Price of shares issued net of underwriting discount (in dollars per share)			$ 105.07
Common Stock [Member] | Over-Allotment Option [Member]
Subsequent Event [Line Items]
Shares issued			3,504,672
Proceeds from issuance of shares			$ 367.0
Subsequent Event [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Shares issued	11,212,500
Subsequent Event [Member] | Common Stock [Member] | Public Offering [Member]
Subsequent Event [Line Items]
Shares issued	9,750,000
Price of shares issued (in dollars per share)	$ 113.75
Price of shares issued net of underwriting discount (in dollars per share)	$ 111.87
Proceeds from issuance of shares	$ 163.6
Subsequent Event [Member] | Common Stock [Member] | Over-Allotment Option [Member]
Subsequent Event [Line Items]
Shares issued	1,462,500
Proceeds from issuance of shares	$ 163.6
Subsequent Event [Member] | Sempra Energy [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Share price (in dollars per share)									$ 117.30
Subsequent Event [Member] | Sempra Energy [Member] | Series B Preferred Stock [Member]
Subsequent Event [Line Items]
Shares issued	5,750,000
Stated rate of debt	6.75%
Conversion price per share (in dollars per share)	$ 100.00
Conversion price per share net of underwriting discount (in dollars per share)	98.35
Liquidation preference (in dollars per share)	$ 100
Proceeds from issuance	$ 565.5
Threshold appreciation price (in dollars per share)	$ 136.50
Share dividends issued, percentage of weighted average share price	97.00%
Number of shares issuable	4,900,000
Subsequent Event [Member] | Sempra Energy [Member] | Series B Preferred Stock [Member] | Minimum [Member]
Subsequent Event [Line Items]
Threshold appreciation price (in dollars per share)	$ 113.75
Shares issuable for each instrument	73.26%
Subsequent Event [Member] | Sempra Energy [Member] | Series B Preferred Stock [Member] | Maximum [Member]
Subsequent Event [Line Items]
Threshold appreciation price (in dollars per share)	$ 136.50
Shares issuable for each instrument	87.91%
Subsequent Event [Member] | Sempra Energy [Member] | Series B Preferred Stock [Member] | Over-Allotment Option [Member]
Subsequent Event [Line Items]
Shares issued	750,000
Forecast [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Proceeds from issuance of shares								$ 1,091.0
Forecast [Member] | Common Stock [Member] | Over-Allotment Option [Member]
Subsequent Event [Line Items]
Proceeds from issuance of shares								$ 1,254.0

[1] As adjusted for the retrospective adoption of ASU 2016-18, which we discuss in Note 2.