EMPLOYEE RETIREMENT PLANS - Net Periodic Pension Cost for Defined-benefit Pension Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net periodic pension cost for the company's defined-benefit pension plans
Pre-tax net loss from accumulated other comprehensive income (loss) into net periodic pension cost	$ 19
Qualified
Net periodic pension cost for the company's defined-benefit pension plans
Service cost	3	$ 3	$ 3
Interest cost	47	47	44
Expected return on plan assets	(46)	(45)	(40)
Amortization of net loss	18	11	16
Net periodic pension cost	22	16	23
Non-Qualified
Net periodic pension cost for the company's defined-benefit pension plans
Interest cost	7	7	6
Amortization of net loss	3	2	2
Net periodic pension cost	$ 10	$ 9	$ 8