Preferred and Common Stock - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended			1 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 30, 2014	Mar. 31, 2014
Class of Stock [Line Items]
Public offering of preferred stock		$ 1,250
Depository shares		25,000,000
Interest in preferred stock		0.1
Proceeds from public offering		1,213
Preferred stock dividend declared				$ 3.75	$ 3.75
Common Stock authorized	1,800,000,000		1,800,000,000
Common stock, par value per share	$ 1		$ 1
Common stock issued, in shares	1,303,813,830		1,303,813,830	1,177,906,867
Common stock, dividends yield	$ 0.03		$ 0.12	$ 0.12	$ 0.12
Stock options granted, vesting period			3 years	3 years	3 years
Stock options granted, contractual term			10 years
Stock awards, vesting period			Three-year
Stock based compensation expense, before tax			87	71	67
Stock based compensation expense, after tax			58	48	46
Stock based compensation expense, stock awards percentage			80.00%	70.00%	60.00%
Unrecognized compensation costs on non-vested stock option grants (pretax)	64		64
Unrecognized compensation costs on non-vested stock option awards (pretax)	64		64
Unrecognized compensation costs on non-vested awards, weighted average period of recognition in years			1 year 7 months 6 days
Expense related to the acceleration of expense related to retirement-eligible employees			15	14	13
Stock option granted, Fair value			2.84	2.24	3.11
Average risk-free interest rate, minimum			0.06%
Average risk-free interest rate, maximum			2.88%
Dividend yield			1.40%
Volatility, minimum			30.00%
Volatility, maximum			40.00%
Annual pre- and post-vesting forfeitures			7.00%
Exercise behavior			45.00%
Life (years)			6 years
Number of options, Outstanding weighted average remaining contractual life			6 years 4 months 28 days
Total intrinsic value of options outstanding	144		144
Stock options vested			18,100,000
Stock option exercisable			18,100,000
Weighted average remaining contractual life, vested and exercisable			5 years 2 months 23 days
Weighted average exercise price, vested and exercisable	$ 12.13		$ 12.13
Total intrinsic value of options vested and exercisable	68		68
Cash received from option exercises			150	13	12
Total tax benefit realized from these exercises			28	1	1
Total intrinsic value of options exercised			84	2	2
2009 [Member]
Class of Stock [Line Items]
Stock options granted, contractual term			6 years
Stock options, outstanding	2,000,000		2,000,000
Stock options expiry period			2015
Preferred Class A [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized	660,000		660,000
Preferred stock par value	$ 100		$ 100
Cumulative dividend preference per share			$ 3.75
Preferred stock, shares outstanding	546,024		546,024	546,024
Preferred stock dividend declared			$ 3.75
Preferred Class B [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized	10,000,000		10,000,000
Preferred stock par value	$ 1		$ 1
Preferred stock, shares outstanding	$ 2.5		$ 2.5
Preferred stock dividend declared			$ 7.53993
5.25% Convertible Notes Due 2014 [Member]
Class of Stock [Line Items]
Common stock issued, in shares							89,000,000
Debt Instrument, Interest Rate, Stated Percentage							5.25%
Firth Rixson [Member]
Class of Stock [Line Items]
Issuance of common stock			37,000,000			37,000,000
IPO [Member]
Class of Stock [Line Items]
Underwriter 30-day common stock options			30 days
IPO [Member] | Depository Shares [Member]
Class of Stock [Line Items]
Additional shares granted			3,750,000
Maximum [Member]
Class of Stock [Line Items]
Preferred stock conversion price	$ 30.9406		$ 30.9406
Minimum [Member]
Class of Stock [Line Items]
Preferred stock conversion price	$ 25.7838		$ 25.7838
Class B Mandatory Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Percentage ownership		5.375%
Mandatory Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock par value		$ 1
Preferred stock liquidation preference		$ 500
Preferred share		2,500,000
Preferred stock dividend declared			$ 26.8750
Preferred stock conversion date			Oct. 01, 2017
Mandatory Convertible Preferred Stock [Member] | IPO [Member]
Class of Stock [Line Items]
Additional shares granted			375,000
Mandatory Convertible Preferred Stock [Member] | Maximum [Member]
Class of Stock [Line Items]
Preferred stock conversion price	$ 30.9406		$ 30.9406
Mandatory Convertible Preferred Stock [Member] | Minimum [Member]
Class of Stock [Line Items]
Preferred stock conversion price	$ 25.2994		$ 25.2994
Mandatory Convertible Preferred Stock [Member] | Minimum [Member] | Anti - Dilution Adjustments [Member]
Class of Stock [Line Items]
Preferred stock conversion price	$ 25.7838		$ 25.7838