Preferred and Common Stock - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended				3 Months Ended		9 Months Ended	12 Months Ended
	Jul. 31, 2015 shares	Mar. 31, 2015 shares	Nov. 30, 2014 shares	Jun. 30, 2014 shares	Dec. 31, 2015 USD ($) $ / shares shares	Mar. 31, 2014 $ / shares shares	Sep. 30, 2014 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares
Class of Stock [Line Items]
Public offering of preferred stock | $							$ 1,250,000
Depository shares | shares							25,000,000
Interest in preferred stock							0.1
Proceeds from public offering | $							$ 1,213,000
Preferred stock dividend declared										$ 3.75
Common Stock authorized | shares					1,800,000,000			1,800,000,000
Common stock, par value per share					$ 1			$ 1
Common stock issued, in shares | shares					1,391,211,244			1,391,211,244	1,303,813,830
Common stock, dividends yield					$ 0.03			$ 0.12	$ 0.12	$ 0.12
Common stock reserved for future issuance | shares					77,000,000			77,000,000
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 | $								$ 92,000	$ 87,000	$ 71,000
Stock based compensation expense, after tax | $								$ 61,000	$ 58,000	$ 48,000
Stock based compensation expense, stock awards percentage								80.00%	80.00%	70.00%
Unrecognized compensation costs on non-vested stock option grants (pretax) | $					$ 71,000			$ 71,000
Unrecognized compensation costs on non-vested stock option awards (pretax) | $					0			$ 0
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 | $								$ 17,000	$ 15,000	$ 14,000
Stock option granted, Fair value | $								$ 4,470	2,840	2,240
Average risk-free interest rate, minimum								0.07%
Average risk-free interest rate, maximum								1.83%
Dividend yield								0.80%
Volatility, minimum								32.00%
Volatility, maximum								41.00%
Annual pre- and post-vesting forfeitures								7.00%
Exercise behavior								50.00%
Life (years)								5 years 10 months 24 days
Number of options, Outstanding weighted average remaining contractual life								6 years 29 days
Total intrinsic value of options outstanding | $					$ 8,000			$ 8,000
Stock options vested | shares								23,300,000
Stock option exercisable | shares								23,300,000
Weighted average remaining contractual life, vested and exercisable								5 years 3 months
Weighted average exercise price, vested and exercisable					$ 11.82			$ 11.82
Total intrinsic value of options vested and exercisable | $					$ 5,000			$ 5,000
Cash received from option exercises | $								25,000	150,000	13,000
Total tax benefit realized from these exercises | $								6,000	28,000	1,000
Total intrinsic value of options exercised | $								$ 19,000	$ 84,000	$ 2,000
Preferred Class A [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized | shares					660,000			660,000
Preferred stock par value					$ 100			$ 100
Cumulative dividend preference per share								$ 3.75
Preferred stock, shares outstanding | shares					546,024			546,024	546,024
Preferred stock dividend declared								$ 3.75	$ 3.75
Preferred Class B [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized | shares					10,000,000			10,000,000
Preferred stock par value					$ 1			$ 1
Preferred stock, shares outstanding | $					$ 2,500			$ 2,500	$ 2,500
Preferred stock dividend declared								$ 26.8750	$ 7.53993
RTI [Member]
Class of Stock [Line Items]
Number of common stock shares issued in a part of acquisition | shares	87,000,000	87,397,414
Firth Rixson [Member]
Class of Stock [Line Items]
Number of common stock shares issued in a part of acquisition | shares				36,523,010
Issuance of common stock | shares			37,000,000						37,000,000
5.25% Convertible Notes Due 2014 [Member]
Class of Stock [Line Items]
Common stock, par value per share						$ 89
Common stock issued, in shares | shares						89,000,000
Debt Instrument, Interest Rate, Stated Percentage						5.25%			5.25%
Stock option exercisable | shares						89,000,000			89,000,000
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 | shares							2,500,000
Preferred stock dividend declared								$ 26.8750
Preferred stock conversion date								Oct. 01, 2017
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