CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (4,025)	$ (12,089)	$ (745)
Defined benefit plans:
Actuarial losses arising during the period	(88)	(5)	(166)
Amortization of unrecognized amounts included in net periodic benefit costs	44	38	25
Foreign exchange (losses) gains	(1)	8	1
Unrealized gains (losses) on securities	2	0	(1)
Other comprehensive (loss) income	(43)	41	(141)
Total comprehensive loss	(4,068)	(12,048)	(886)
Total comprehensive income attributable to noncontrolling interests	(292)	(106)	(521)
Gain on redemption and preferred dividends attributable to noncontrolling interests	161	(41)	(40)
Total comprehensive loss attributable to common stockholders	$ (4,199)	$ (12,195)	$ (1,447)