Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenues	$ 3,263	$ 3,171	$ 10,490	$ 9,771
Costs and expenses:
Operating	1,922	1,862	6,506	5,940
Selling, general and administrative	549	525	1,605	1,520
Depreciation and amortization	56	55	168	166
Restructuring and other corporate matters	46	0	90	0
Total costs and expenses	2,573	2,442	8,369	7,626
Operating income (loss)	690	729	2,121	2,145
Interest expense	(115)	(116)	(349)	(336)
Interest income	12	17	43	45
Loss on early extinguishment of debt	0	(5)	0	(5)
Other items, net	(17)	(19)	(52)	(56)
Earnings (loss) from continuing operations before income taxes and equity in earnings (loss) of investee companies	570	606	1,763	1,793
Provision for income taxes	(64)	(172)	(312)	(479)
Equity in loss of investee companies, net of tax	(18)	(16)	(52)	(45)
Net earnings from continuing operations	488	418	1,399	1,269
Net earnings (loss) from discontinued operations, net of tax	0	174	0	(871)
Net earnings	$ 488	$ 592	$ 1,399	$ 398
Basic net earnings (loss) per common share:
Basic net earnings from continuing operations (in dollars per share)	$ 1.30	$ 1.04	$ 3.70	$ 3.13
Basic net earnings (loss) from discontinued operations (in dollars per share)	0.00	0.43	0.00	(2.15)
Basic net earnings (in dollars per share)	1.30	1.48	3.70	0.98
Diluted net earnings (loss) per common share:
Diluted net earnings from continuing operations (in dollars per share)	1.29	1.03	3.66	3.10
Diluted net earnings (loss) from discontinued operations (in dollars per share)	0.00	0.43	0.00	(2.12)
Diluted net earnings (in dollars per share)	$ 1.29	$ 1.46	$ 3.66	$ 0.97
Weighted average number of common shares outstanding:
Basic (in shares)	375	401	378	405
Diluted (in shares)	379	406	382	410
Dividends per common share (in dollars per share)	$ 0.18	$ 0.18	$ 0.54	$ 0.54