EMPLOYEE RETIREMENT PLANS - Qualified Defined-benefit Pension Plan Assets at Fair Value by Level within the Fair Value Hierarchy (Details) - Qualified - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value
Private equity funds	$ 670,000,000	$ 695,000,000	$ 717,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	376,000,000	259,000,000
UNITED STATES | Common And Preferred Stock [Member]
Fair Value
Private equity funds	102,000,000	191,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	21,000,000	47,000,000
UNITED STATES | Private Equity And Hedge Funds [Member]
Fair Value
Private equity funds	32,000,000	36,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	0	0
UNITED STATES | Corporate Debt Securities [Member]
Fair Value
Private equity funds	136,000,000	57,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	102,000,000	0
UNITED STATES | US Treasury and Government [Member]
Fair Value
Private equity funds	132,000,000	53,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	130,000,000	31,000,000
UNITED STATES | Common Collective Trust Fund [Member]
Fair Value
Private equity funds	4,000,000	6,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	0	0
UNITED STATES | Short Term And Other Investments [Member]
Fair Value
Private equity funds	1,000,000	2,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	0	0
International [Member] | Common And Preferred Stock [Member]
Fair Value
Private equity funds	126,000,000	191,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	89,000,000	125,000,000
International [Member] | Private Equity And Hedge Funds [Member]
Fair Value
Private equity funds	61,000,000	59,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	34,000,000	35,000,000
International [Member] | Corporate Debt Securities [Member]
Fair Value
Private equity funds	1,000,000	28,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	0	21,000,000
International [Member] | Foreign Government Debt Securities [Member]
Fair Value
Private equity funds	62,000,000	59,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	0	0
International [Member] | Buy-in Annuity [Member]
Fair Value
Private equity funds	11,000,000	12,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	0	0
International [Member] | Short Term And Other Investments [Member]
Fair Value
Private equity funds	2,000,000	1,000,000
Defined Benefit Plan, Net Asset Value of Plan Assets	0	0
Fair Value, Inputs, Level 1
Fair Value
Private equity funds	184,000,000	289,000,000
Fair Value, Inputs, Level 1 | UNITED STATES | Common And Preferred Stock [Member]
Fair Value
Private equity funds	81,000,000	144,000,000
Fair Value, Inputs, Level 1 | UNITED STATES | Private Equity And Hedge Funds [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 1 | UNITED STATES | Corporate Debt Securities [Member]
Fair Value
Private equity funds	34,000,000	31,000,000
Fair Value, Inputs, Level 1 | UNITED STATES | US Treasury and Government [Member]
Fair Value
Private equity funds	0	15,000,000
Fair Value, Inputs, Level 1 | UNITED STATES | Common Collective Trust Fund [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 1 | UNITED STATES | Short Term And Other Investments [Member]
Fair Value
Private equity funds	1,000,000	2,000,000
Fair Value, Inputs, Level 1 | International [Member] | Common And Preferred Stock [Member]
Fair Value
Private equity funds	37,000,000	66,000,000
Fair Value, Inputs, Level 1 | International [Member] | Private Equity And Hedge Funds [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 1 | International [Member] | Corporate Debt Securities [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 1 | International [Member] | Foreign Government Debt Securities [Member]
Fair Value
Private equity funds	29,000,000	31,000,000
Fair Value, Inputs, Level 1 | International [Member] | Buy-in Annuity [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 1 | International [Member] | Short Term And Other Investments [Member]
Fair Value
Private equity funds	2,000,000	0
Fair Value, Inputs, Level 2
Fair Value
Private equity funds	51,000,000	87,000,000
Fair Value, Inputs, Level 2 | UNITED STATES | Common And Preferred Stock [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 2 | UNITED STATES | Private Equity And Hedge Funds [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 2 | UNITED STATES | Corporate Debt Securities [Member]
Fair Value
Private equity funds	0	26,000,000
Fair Value, Inputs, Level 2 | UNITED STATES | US Treasury and Government [Member]
Fair Value
Private equity funds	2,000,000	7,000,000
Fair Value, Inputs, Level 2 | UNITED STATES | Common Collective Trust Fund [Member]
Fair Value
Private equity funds	4,000,000	6,000,000
Fair Value, Inputs, Level 2 | UNITED STATES | Short Term And Other Investments [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 2 | International [Member] | Common And Preferred Stock [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 2 | International [Member] | Private Equity And Hedge Funds [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 2 | International [Member] | Corporate Debt Securities [Member]
Fair Value
Private equity funds	1,000,000	7,000,000
Fair Value, Inputs, Level 2 | International [Member] | Foreign Government Debt Securities [Member]
Fair Value
Private equity funds	33,000,000	28,000,000
Fair Value, Inputs, Level 2 | International [Member] | Buy-in Annuity [Member]
Fair Value
Private equity funds	11,000,000	12,000,000
Fair Value, Inputs, Level 2 | International [Member] | Short Term And Other Investments [Member]
Fair Value
Private equity funds	0	1,000,000
Fair Value, Inputs, Level 3
Fair Value
Private equity funds	59,000,000	60,000,000
Fair Value, Inputs, Level 3 | UNITED STATES | Common And Preferred Stock [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 3 | UNITED STATES | Private Equity And Hedge Funds [Member]
Fair Value
Private equity funds	32,000,000	36,000,000
Fair Value, Inputs, Level 3 | UNITED STATES | Corporate Debt Securities [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 3 | UNITED STATES | US Treasury and Government [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 3 | UNITED STATES | Common Collective Trust Fund [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 3 | UNITED STATES | Short Term And Other Investments [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 3 | International [Member] | Common And Preferred Stock [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 3 | International [Member] | Private Equity And Hedge Funds [Member]
Fair Value
Private equity funds	27,000,000	24,000,000
Fair Value, Inputs, Level 3 | International [Member] | Corporate Debt Securities [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 3 | International [Member] | Foreign Government Debt Securities [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 3 | International [Member] | Buy-in Annuity [Member]
Fair Value
Private equity funds	0	0
Fair Value, Inputs, Level 3 | International [Member] | Short Term And Other Investments [Member]
Fair Value
Private equity funds	$ 0	$ 0