Stockholders' Equity Stock Repurchase Program (Details) - 2016 Stock Repurchase Program - USD ($) shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Jan. 28, 2016
Equity, Class of Treasury Stock [Line Items]
Authorized amount			$ 12,000
Repurchases of common stock (in shares)	12	13
Repurchases of common stock, amount	$ 834	$ 1,000
Remaining authorized repurchase amount	$ 4,300

Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

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