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Income Taxes - Reconciliation of U.S. Federal Statutory Rate to Arconic's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
U.S. federal statutory rate	35.00%	35.00%	35.00%
Taxes on foreign operations	(10.20%)	2.50%	(9.40%)
Permanent differences on restructuring and other charges and asset disposals	(107.80%)	3.60%	(1.00%)
Non-deductible acquisition costs	8.40%	7.10%	7.30%
Statutory tax rate and law changes	(15.70%)	(1.00%)	78.80%
Tax holidays	(0.80%)	(3.90%)	38.50%
Tax credits	(1.20%)	(2.80%)	(1.90%)
Changes in valuation allowances	426.80%	145.80%	17.30%
Impairment of goodwill		4.80%
Company-owned life insurance/split-dollar net premiums	23.00%	(3.00%)	(9.60%)
Changes in uncertain tax positions	2.30%	(2.00%)	(5.60%)
Other	(3.30%)	(0.90%)	(4.60%)
Effective tax rate	356.50%	185.20%	154.00%

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