CONSOLIDATED CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive loss
Beginning balance at Dec. 31, 2017	$ 20,572	$ 179	$ (9,168)	$ 7,884	$ 21,935	$ (258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	708				708
Other comprehensive income, net of tax	4					4
Dividends on common stock	(594)				(594)
Issuance of common stock, net	32			32
Reclassification of stranded tax effects					58	(58)
Ending balance at Mar. 31, 2018	20,722	179	(9,168)	7,916	22,107	(312)
Beginning balance at Dec. 31, 2018	21,330	179	(10,473)	8,046	23,750	(172)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	631				631
Other comprehensive income, net of tax	4					4
Dividends on common stock	(586)				(586)
Issuance of common stock, net	37			37
Purchases of treasury stock	(180)		(180)
Ending balance at Mar. 31, 2019	$ 21,236	$ 179	$ (10,653)	$ 8,083	$ 23,795	$ (168)