Capital Actions (Capital Actions ASRs) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2019	Mar. 31, 2018
Capital Actions
Shares acquired for treasury			$ 913	$ 318
March 2019 ASR | March 2018 Repurchase Program
Capital Actions
Repurchase Date	[1]	Mar. 27, 2019
Shares acquired for treasury		$ 913
Shares repurchased on repurchase date		31,779,280

[1] This accelerated share repurchase transaction consists of two supplemental confirmations each with a notional amount of $456.5 million. The settlement of the transaction is expected to occur on or before June 28, 2019.