DEBT AND FINANCING COSTS - Additional Information (Detail) £ in Millions	1 Months Ended	6 Months Ended
	Mar. 31, 2018 USD ($) Contract	Jun. 30, 2018 USD ($)	Jun. 30, 2018 GBP (£)	Jun. 30, 2018 GBP (£)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Number of credit facilities terminated | Contract	2
Write off of deferred loan costs	$ 4,000,000
Commercial Paper
Debt Instrument [Line Items]
Debt instrument, face amount		$ 3,500,000,000.0
Debt instrument term		270 days	270 days
Letter of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity		$ 3,000,000,000.0
Line of credit facility, committed amount		2,080,000,000
Line of credit facility aggregate commitment amount | £				£ 129.1
Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, number of extension options | Contract	2
Extended financing agreement term	1 year
Credit facility maximum borrowing capacity		5,000,000,000.0
Line of credit facility, committed amount		4,000,000,000
Letters of credit outstanding, amount		0
Credit Facility $3.5 Billion
Debt Instrument [Line Items]
Debt extinguished amount		3,500,000,000
Credit Facility £900 Million
Debt Instrument [Line Items]
Debt extinguished amount | £			£ 900.0
Unsecured Debt
Debt Instrument [Line Items]
Debt instrument, face amount		8,430,000,000			$ 8,580,000,000
Unsecured Debt | 6.9% senior notes due September 15, 2018
Debt Instrument [Line Items]
Debt instrument, face amount		$ 400,000,000
Debt instrument, stated interest rate		6.90%		6.90%
Unsecured Debt | 7.0% senior notes due February 1, 2018
Debt Instrument [Line Items]
Debt instrument, face amount					$ 150,000,000
Debt instrument, stated interest rate					7.00%