Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Treasury Stock	Previously Reported Retained Earnings	Previously Reported Accumulated Other Comprehensive (Loss) Income
Total stockholder's equity at beginning of period at Dec. 31, 2015		$ 683	$ 2,153			$ (78)	$ 9,313	$ (315)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			20			5
Dividends to common stockholders ($3.30, $3.10, and $3.00 per share)				$ (813)
Net income	$ 859			859
Other comprehensive (loss) income	142				$ 142
Total stockholder's equity at end of period at Dec. 31, 2016	11,969	683	2,173	9,359	(173)	(73)	9,359	(173)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			2			13
Dividends to common stockholders ($3.30, $3.10, and $3.00 per share)				(844)
Net income	899			899
Other comprehensive (loss) income	205				205
Total stockholder's equity at end of period at Dec. 31, 2017	12,244	683	2,175	9,414	32	(60)	$ 9,414	$ 32
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			17			3
Dividends to common stockholders ($3.30, $3.10, and $3.00 per share)				(900)
Net income	813			813
Other comprehensive (loss) income	(894)				(894)
Total stockholder's equity at end of period at Dec. 31, 2018	$ 11,217	$ 683	$ 2,192	$ 9,277	$ (878)	$ (57)