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Stockholders' Equity (Details) - $ / shares | 2 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Feb. 21, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Jan. 31, 2017 | May 31, 2015
Stockholders' equity |  |  |  |  |  |
Common stock, shares authorized (in shares) |  | 153,000,000 | 153,000,000 |  |  |
Subsequent Event |  |  |  |  |  |
Share repurchase activity |  |  |  |  |  |
Shares repurchased (in shares) | 400,000 |  |  |  |  |
Average price (in usd per share) | $ 159.91 |  |  |  |  |
Preferred Stock |  |  |  |  |  |
Stockholders' equity |  |  |  |  |  |
Preferred stock, shares authorized (in shares) |  | 5,000,000.0 |  |  |  |
Common Stock |  |  |  |  |  |
Share repurchase activity |  |  |  |  |  |
Shares repurchased (in shares) |  | 200,000 | 1,700,000 | 1,200,000 |  |
Average price (in usd per share) |  | $ 161.16 | $ 209.39 | $ 204.72 |  |
Common Stock | 2017 Authorization |  |  |  |  |  |
Stockholders' equity |  |  |  |  |  |
Stock repurchase program, authorized amount (in shares) |  | 200,000 |  |  |  |
Share repurchase activity |  |  |  |  |  |
Average price (in usd per share) |  | $ 161.16 |  |  |  |
Common Stock | 2017 Authorization | Subsequent Event |  |  |  |  |  |
Stockholders' equity |  |  |  |  |  |
Stock repurchase program, authorized amount (in shares) |  |  |  |  | 1,900,000 |
Common Stock | 2015 Authorization |  |  |  |  |  |
Stockholders' equity |  |  |  |  |  |
Stock repurchase program, authorized amount (in shares) |  |  |  |  |  | 3,000,000
Voting Common Stock |  |  |  |  |  |
Stockholders' equity |  |  |  |  |  |
Common stock, shares authorized (in shares) |  | 150,000,000 |  |  |  |
Class B Non-Voting Common Stock |  |  |  |  |  |
Stockholders' equity |  |  |  |  |  |
Common stock, shares authorized (in shares) |  | 3,000,000.0 |  |  |  |

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