Acquisitions and Divestitures - Summary of Final Allocation of Purchase Price by Major Asset Acquired and Liability Assumed, Amount of Goodwill Recognized (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Assets:
Goodwill	$ 5,384	$ 5,401
RTI [Member]
Assets:
Cash	303
Receivables from customers	94
Inventories	483
Prepaid expenses and other current assets	47
Properties, plants, and equipment	321
Goodwill	298
Other noncurrent assets	60
Total assets	1,606
Liabilities:
Accounts payable	86
Other current liabilities	94
Long-term debt due within one year	115
Long-term debt, less amount due within one year	387
Other noncurrent liabilities	111
Total liabilities	793
Equity
Additional capital	60
Total equity	$ 60