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Stockholders' Equity - Additional Information (Details) - USD ($) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Jan. 31, 2018 | Jan. 31, 2017
Class of Stock [Line Items] |  |  |  |  |
Common stock, shares authorized (in shares) | 153,000,000 | 153,000,000 |  |  |
Proceeds from issuance of common stock | $ 9,700,000 | $ 41,900,000 | $ 465,800,000 |  |
Common stock, shares outstanding (in shares) | 58,500,000 | 58,500,000 |  |  |
Forward Equity Agreement |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Proceeds from issuance of common stock | $ 0 |  |  |  |
Stock program, maximum amount authorized |  |  | $ 500,000,000 |  |
Voting Common Stock |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Common stock, shares authorized (in shares) | 150,000,000.0 |  |  |  |
Common Class B |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Common stock, shares authorized (in shares) | 3,000,000.0 |  |  |  |
Common Stock |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Shares repurchased (in shares) | 3,300,000 | 2,400,000 | 200,000 |  |
Average price of stock repurchased (in dollars per share) | $ 150.31 | $ 173.19 | $ 161.16 |  |
Common Stock | Forward Equity Agreement |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Maximum number of shares available for sale under agreement (in shares) |  |  | 2,900,000 |  |
Average share price on forward basis (in dollars per share) |  |  | $ 167.25 |  |
Number of shares issued to settle portion of forward equity sale (in shares) |  |  | 2,700,000 |  |
Proceeds from issuance of common stock |  |  | $ 440,300,000 |  |
Number of shares issued to settle portion of forward equity sale in cash (in shares) |  |  | 200,000 |  |
Average share price of shares settled in cash (in dollars per share) |  |  | $ 144.59 |  |
Common stock, shares outstanding (in shares) |  |  | 0 |  |
Common Stock | January 2018 Program |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Stock repurchase program, number of shares authorized (in shares) |  |  |  | 3,400,000.0 |
Stock repurchase plan, number of remaining shares to be repurchased (in shares) | 1,700,000 |  |  |  |
Common Stock | January 2017 Program |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Stock repurchase program, number of shares authorized (in shares) |  |  |  |  | 1,900,000.0
Stock repurchase plan, number of remaining shares to be repurchased (in shares) | 0 |  |  |  |
Preferred Stock |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Preferred stock, shares authorized (in shares) | 5,000,000.0 |  |  |  |

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