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Stockholders' Equity of the Company - Additional Information (Details) | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Sep. 30, 2018 USD ($) $ / shares shares | Jun. 30, 2018 USD ($) $ / shares shares | Mar. 31, 2018 USD ($) $ / shares shares | Sep. 30, 2018 USD ($) increase $ / shares shares | Dec. 31, 2017 USD ($) $ / shares shares | Aug. 31, 2016 USD ($)
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |
Authorized capital stock (shares) | 260,000,000 |  |  | 260,000,000 |  |
Authorized shares, par value (in dollars per share) | $ / shares | $ 0.01 |  |  | $ 0.01 |  |
Common stock, shares authorized (in shares) | 160,000,000 |  |  | 160,000,000 | 160,000,000 |
Common stock, par value (in dollars per share) | $ / shares | $ 0.01 |  |  | $ 0.01 | $ 0.01 |
Excess stock, shares authorized (shares) | 75,000,000 |  |  | 75,000,000 |  |
Excess stock, par value (in dollars per share) | $ / shares | $ 0.01 |  |  | $ 0.01 |  |
Preferred stock, shares authorized (shares) | 25,000,000 |  |  | 25,000,000 |  |
Preferred stock, par value (in dollars per share) | $ / shares | $ 0.01 |  |  | $ 0.01 |  |
Excess shares issued (shares) | 0 |  |  | 0 |  |
Shares repurchased | 252,947 | 3,479,552 | 3,653,928 |  | 8,342,411 |
Average price paid per share (in dollars per share) | $ / shares | $ 99.75 | $ 97.22 | $ 97.07 |  | $ 101.64 |
2016 Repurchase Program |  |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |
Stock repurchase program, authorized amount | $ |  | $ 500,000,000 |  |  | $ 500,000,000 | $ 1,000,000,000.0
Number of increases to share repurchase program | increase |  |  |  | 2 |  |
Shares repurchased | 15,728,838 | 15,475,891 | 11,996,339 |  | 8,342,411 |
Maximum approximate dollar value of shares that may yet be purchased under the plan | $ | $ 433,600,000 | $ 458,900,000 | $ 797,200,000 | $ 433,600,000 | $ 1,152,000,000 |
Stock repurchase program, authorized amount | $ | $ 2,000,000,000.0 |  |  | $ 2,000,000,000.0 |  |

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