SHAREHOLDERS' INTEREST - Changes in amounts included in our cumulative other comprehensive income (loss) by component (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Beginning balance	$ (686)	$ (1,558)
Other comprehensive income (loss) before reclassifications	(1,075)	1,156
Income taxes	377	(428)
Net other comprehensive income (loss) before reclassifications	(698)	728
Amounts reclassified from cumulative other comprehensive income (loss)(1)	(19)	219
Income taxes	10	(75)
Net amounts reclassified from cumulative other comprehensive income (loss)	(9)	144
Total other comprehensive income (loss)	(707)	872
Ending balance	(1,393)	(686)
Foreign currency translation adjustments
Beginning balance	354	413
Other comprehensive income (loss) before reclassifications	(50)	(59)
Income taxes	0	0
Net other comprehensive income (loss) before reclassifications	(50)	(59)
Amounts reclassified from cumulative other comprehensive income (loss)(1)	0	0
Income taxes	0	0
Net amounts reclassified from cumulative other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	(50)	(59)
Ending balance	304	354
Unrealized gains on available-for-sale securities
Beginning balance	6	4
Other comprehensive income (loss) before reclassifications	0	2
Income taxes	0	0
Net other comprehensive income (loss) before reclassifications	0	2
Amounts reclassified from cumulative other comprehensive income (loss)(1)	0	0
Income taxes	0	0
Net amounts reclassified from cumulative other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	0	2
Ending balance	6	6
Pension | Actuarial losses
Beginning balance	(1,066)	(1,942)
Other comprehensive income (loss) before reclassifications	(1,008)	1,123
Income taxes	369	(394)
Net other comprehensive income (loss) before reclassifications	(639)	729
Amounts reclassified from cumulative other comprehensive income (loss)(1)	125	221
Income taxes	(43)	(74)
Net amounts reclassified from cumulative other comprehensive income (loss)	82	147
Total other comprehensive income (loss)	(557)	876
Ending balance	(1,623)	(1,066)
Pension | Prior service credits (costs)
Beginning balance	(19)	(23)
Other comprehensive income (loss) before reclassifications	1	0
Income taxes	0	0
Net other comprehensive income (loss) before reclassifications	1	0
Amounts reclassified from cumulative other comprehensive income (loss)(1)	5	7
Income taxes	(2)	(3)
Net amounts reclassified from cumulative other comprehensive income (loss)	3	4
Total other comprehensive income (loss)	4	4
Ending balance	(15)	(19)
Other Postretirement Benefits | Actuarial losses
Beginning balance	(111)	(137)
Other comprehensive income (loss) before reclassifications	(6)	24
Income taxes	1	(7)
Net other comprehensive income (loss) before reclassifications	(5)	17
Amounts reclassified from cumulative other comprehensive income (loss)(1)	12	14
Income taxes	(4)	(5)
Net amounts reclassified from cumulative other comprehensive income (loss)	8	9
Total other comprehensive income (loss)	3	26
Ending balance	(108)	(111)
Other Postretirement Benefits | Prior service credits (costs)
Beginning balance	150	127
Other comprehensive income (loss) before reclassifications	(12)	66
Income taxes	7	(27)
Net other comprehensive income (loss) before reclassifications	(5)	39
Amounts reclassified from cumulative other comprehensive income (loss)(1)	(161)	(23)
Income taxes	59	7
Net amounts reclassified from cumulative other comprehensive income (loss)	(102)	(16)
Total other comprehensive income (loss)	(107)	23
Ending balance	$ 43	$ 150