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Preferred and Common Stock - Additional Information (Detail) |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended | 14 Months Ended |
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Oct. 02, 2017 $ / shares shares | Oct. 05, 2016 $ / shares shares | Aug. 31, 2016 shares | Jul. 23, 2015 shares | Jul. 22, 2015 shares | Aug. 31, 2016 shares | Aug. 31, 2016 USD ($) shares | Aug. 30, 2016 USD ($) | Jul. 31, 2015 USD ($) $ / shares shares | Sep. 30, 2014 USD ($) $ / shares shares | Dec. 31, 2017 USD ($) $ / shares shares | Sep. 30, 2017 $ / shares | Jun. 30, 2017 $ / shares shares | Mar. 31, 2017 $ / shares | Dec. 31, 2016 USD ($) $ / shares shares | Sep. 30, 2016 $ / shares | Jun. 30, 2016 $ / shares | Mar. 31, 2016 $ / shares | Sep. 30, 2015 $ / shares | Jun. 30, 2015 $ / shares | Mar. 31, 2015 $ / shares | Dec. 31, 2017 USD ($) class_of_stock $ / shares shares | Dec. 31, 2016 USD ($) $ / shares shares | Dec. 31, 2015 USD ($) $ / shares shares | Oct. 04, 2016 shares | Dec. 31, 2014 shares
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, number of classes | class_of_stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |
Preferred stock par value (usd per share) | $ / shares |  |  |  |  |  |  |  |  |  | $ 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public offering of preferred stock |  |  |  |  |  |  |  |  |  | $ 1,250,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Depository shares sold (in shares) | shares | 24,022 |  |  |  |  |  |  |  |  | 25,000,000 |  |  | 12,958,767 |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from public offering |  |  |  |  |  |  |  |  |  | $ 1,213,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest in preferred stock | 0.10 |  |  |  |  |  |  |  |  | 0.10 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Conversion of stock, shares converted (in shares) | shares | 31,420 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reverse stock split ratio |  | 0.3333 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock outstanding (in shares) | shares |  | 400,000,000 |  |  |  |  |  |  |  |  | 481,416,537 |  |  |  | 438,519,780 |  |  |  |  |  |  | 481,416,537 | 438,519,780 | 1,310,160,141 | 1,300,000,000.0 | 1,216,663,661
Common stock, par value per share (usd pe share) | $ / shares |  | $ 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock decrease |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 877,000,000 |  |  |
Additional capital increase (decrease) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 877,000,000 |  |  |
Common stock authorized (in shares) | shares |  | 600,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,800,000,000 |
Treasury stock retirement (in shares) | shares |  |  | 25,000,000 |  |  | 76,000,000 | 76,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retirement of treasury stock |  |  |  |  |  |  |  | $ 76,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |
Treasury stock, value |  |  |  |  |  |  |  |  |  |  | $ 0 |  |  |  | $ 0 |  |  |  |  |  |  | $ 0 | $ 0 |  |  |
Common stock issued (in shares) | shares |  |  |  |  |  |  |  |  |  |  | 481,416,537 |  |  |  |  |  |  |  |  |  |  | 481,416,537 |  |  |  |
Dividends paid per share (usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 0.06 | $ 0.06 | $ 0.06 | $ 0.06 | $ 0.09 | $ 0.09 | $ 0.09 | $ 0.09 | $ 0.09 | $ 0.09 | $ 0.09 |  |  | $ 0.36 |  |
Common stock, dividends yield (usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 0.06 |  |  |  |  |  |  |  |  |  |  | $ 0.24 | $ 0.36 | $ 0.12 |  |
Document Fiscal Year Focus |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2017 |  |  |  |
Common stock reserved for future issuance (in shares) | shares |  |  |  |  |  |  |  |  |  |  | 47,000,000 |  |  |  |  |  |  |  |  |  |  | 47,000,000 |  |  |  |
Common stock, number of shares available for grant | shares |  |  |  |  |  |  |  |  |  |  | 43,000,000 |  |  |  |  |  |  |  |  |  |  | 43,000,000 |  |  |  |
Stock based compensation expense, before tax |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 54,000,000 | $ 76,000,000 | $ 77,000,000 |  |
Stock based compensation expense, after tax |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 36,000,000 | $ 51,000,000 | $ 51,000,000 |  |
Stock based compensation expense, stock awards percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 85.00% | 80.00% | 80.00% |  |
Unrecognized compensation costs on non-vested stock option awards (pretax) |  |  |  |  |  |  |  |  |  |  | $ 0 |  |  |  | $ 0 |  |  |  |  |  |  | $ 0 | $ 0 | $ 0 |  |
Unrecognized compensation costs on non-vested stock option grants (pretax) |  |  |  |  |  |  |  |  |  |  | 43,000,000 |  |  |  |  |  |  |  |  |  |  | $ 43,000,000 |  |  |  |
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 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 15,000,000 | $ 19,000,000 | $ 15,000,000 |  |
Weighted average FMV per award, Granted (in usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 21.86 |  |  |  |
Average risk-free interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2.40% |  |  |  |
Share-based compensation arrangement by share-based payment award, options, grants in period, weighted average grant date fair value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 6.26 | $ 4.78 | $ 10.07 |  |
Volatility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 38.10% | 44.50% | 36.50% |  |
Dividend yield |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.20% |  |  |  |
Annual pre- and post-vesting forfeitures |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6.00% |  |  |  |
Exercise behavior |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 59.00% |  |  |  |
Life (years) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5 years 10 months 24 days |  |  |  |
Number of options, Outstanding weighted average remaining contractual life |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5 years 3 months 29 days |  |  |  |
Total intrinsic value of options outstanding |  |  |  |  |  |  |  |  |  |  | $ 53,000,000 |  |  |  |  |  |  |  |  |  |  | $ 53,000,000 |  |  |  |
Stock options vested (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,400,000 |  |  |  |
Stock option exercisable | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8,900,000 |  |  |  |
Weighted average remaining contractual life, vested and exercisable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 years 1 month 28 days |  |  |  |
Weighted average exercise price, vested and exercisable (in usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 25.90 |  |  |  |  |  |  |  |  |  |  | $ 25.90 |  |  |  |
Total intrinsic value of options vested and exercisable |  |  |  |  |  |  |  |  |  |  | $ 26,000,000 |  |  |  |  |  |  |  |  |  |  | $ 26,000,000 |  |  |  |
Proceeds from exercise of employee stock options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50,000,000 | $ 4,000,000 | $ 25,000,000 |  |
Total tax benefit realized from these exercises |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,000,000 | 0 | 6,000,000 |  |
Total intrinsic value of options exercised |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 13,000,000 | 1,000,000 | 19,000,000 |  |
Restructuring and Other Charges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock based compensation expense, before tax |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (13,000,000) |  |  |  |
Stock Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock options granted, vesting period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |
Share-based compensation arrangement by share-based payment award, expiration period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10 years |  |  |  |
Stock option exercisable | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,000,000 |  |  |  |
Restricted Stock Units (RSUs) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock options granted, contractual term |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |
Share-based compensation arrangement by share-based payment award, award performance period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |
Performance Shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, award performance period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |
Weighted average FMV per award, Granted (in usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 21.99 |  |  |  |
Average risk-free interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.50% |  |  |  |
Volatility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 38.00% |  |  |  |
RTI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of common stock shares issued in a part of acquisition (in shares) | shares |  | 29,000,000 |  | 87,397,414 | 29,132,471 |  |  |  | 29,132,471 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 87,000,000 |
Number of shares to be issued upon conversion | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 14,294,000 |  |  |  |  |  |  |  |  |  |  | $ 14,294,000 |  |  |  |
Debt instrument, convertible, conversion price | $ / shares |  |  |  |  |  |  |  |  | $ 2.8315 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
RTI | Convertible Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, convertible, conversion price | $ / shares |  |  |  |  |  |  |  |  | $ 28.1596 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, amount received upon maturity per one thousand dollars in principal amount of notes held |  |  |  |  |  |  |  |  | $ 1,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
RTI | Tranche Due December 2015 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt due within one year |  |  |  |  |  |  |  |  | 115,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
RTI | Tranche Due October 2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt due within one year |  |  |  |  |  |  |  |  | $ 403,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 403,000,000 |  |
RTI | 1.63% Convertible Notes, Due 2019 | Convertible Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, convertible, conversion rate per bond |  |  |  |  |  |  |  |  |  |  | 0.0355119 |  |  |  |  |  |  |  |  |  |  | 0.0355119 |  |  |  |
Debt instrument, convertible, conversion price | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 28.1596 |  |  |  |  |  |  |  |  |  |  | $ 28.1596 |  |  |  |
Common stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retirement of treasury stock |  |  |  |  |  |  | $ 76,000,000 | 76,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 76,000,000 |  |  |
Number of common stock shares issued in a part of acquisition (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 87,397,414 |  |
Additional capital |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retirement of treasury stock |  |  |  |  |  |  | $ 2,563,000,000 | $ 2,563,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,563,000,000 |  |  |
Class B Mandatory Convertible Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage ownership |  |  |  |  |  |  |  |  |  | 5.375% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Mandatory convertible preferred stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Depository shares sold (in shares) | shares | 24,975,978 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock liquidation preference (usd per share) | $ / shares |  |  |  |  |  |  |  |  |  | $ 500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred shares (in shares) | shares |  |  |  |  |  |  |  |  |  | 2,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest in preferred stock | 0.1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock conversion price (in usd per share) | $ / shares | $ 1.56996 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Conversion of stock, shares converted (in shares) | shares | 39,211,286 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred Class A |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares authorized (in shares) | shares |  |  |  |  |  |  |  |  |  |  | 660,000 |  |  |  |  |  |  |  |  |  |  | 660,000 |  |  |  |
Preferred stock par value (usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 100 |  |  |  |  |  |  |  |  |  |  | $ 100 |  |  |  |
Preferred stock dividend declared (usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3.75 | $ 3.75 | $ 3.75 |  |
Preferred stock, shares outstanding (in shares) | shares |  |  |  |  |  |  |  |  |  |  | 546,024 |  |  |  | 546,024 |  |  |  |  |  |  | 546,024 | 546,024 |  |  |
Preferred Class B |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares authorized (in shares) | shares |  |  |  |  |  |  |  |  |  |  | 10,000,000 |  |  |  |  |  |  |  |  |  |  | 10,000,000 |  |  |  |
Preferred stock par value (usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 1 |  |  |  |  |  |  |  |  |  |  | $ 1 |  |  |  |
Preferred stock dividend declared (usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 20.1563 | $ 26.875 | $ 26.8750 |  |
Preferred stock, shares outstanding (in shares) | shares |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 2,500,000 |  |  |  |  |  |  | 0 | 2,500,000 |  |  |
Preferred stock, dividends, per share, cash paid | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 20.1563 |  |  |  |
Share-based Compensation Award, Tranche One | Stock Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, award vesting rights, percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 33.33% |  |  |  |
Share-based Compensation Award, Tranche Two | Stock Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, award vesting rights, percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 33.33% |  |  |  |
Share-based Compensation Award, Tranche Three | Stock Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, award vesting rights, percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 33.33% |  |  |  |
Twenty Seventeen Awards | Performance Shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock options granted, vesting period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |
Twenty Fifteen And Twenty Sixteen Awards | Share-based Compensation Award, Tranche One | Performance Shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, award vesting rights, percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 33.33% |  |  |  |
Twenty Fifteen And Twenty Sixteen Awards | Share-based Compensation Award, Tranche Two | Performance Shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, award vesting rights, percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 33.33% |  |  |  |
Twenty Fifteen And Twenty Sixteen Awards | Share-based Compensation Award, Tranche Three | Performance Shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, award vesting rights, percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 33.33% |  |  |  |

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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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