EMPLOYEE BENEFITS - Schedule of Net Periodic (Income) Cost (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended			12 Months Ended
	Sep. 01, 2014	Mar. 31, 2015	Mar. 31, 2014		Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 1	$ 1	[1]
Interest cost		12	12	[1]
Expected return on plan assets		(18)	(17)	[1]
Amortization of actuarial loss		4	2	[1]
Net periodic pension (income) cost		(1)	(2)	[1]
Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		1	1	[1]
Interest cost		11	11	[1]
Expected return on plan assets		(18)	(17)	[1]
Amortization of actuarial loss		3	2	[1]
Net periodic pension (income) cost		(3)	(3)	[1]
Assets transferred to Affiliate plans	129				129
Liabilities transferred to Affiliate plans	148				148
Non-Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		0	0	[1]
Interest cost		1	1	[1]
Expected return on plan assets		0	0	[1]
Amortization of actuarial loss		1	0	[1]
Net periodic pension (income) cost		2	1	[1]
Liabilities transferred to Affiliate plans	$ 7				$ 7

[1] Results for the three months ended March 31, 2014 included $129 million in qualified plan assets, $148 million in qualified plan liabilities and $7 million in non-qualified plan liabilities transferred to Affiliates on September 1, 2014.