Stockholders' Equity (Purchases of Common Stock) (Details) - Stock Buyback Program - USD ($) $ in Millions |
12 Months Ended | |
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Dec. 31, 2019 |
Dec. 31, 2018 |
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| Class of Stock [Line Items] | ||
| Number of shares repurchased | 1,006,243 | 2,397,710 |
| Series A Common Stock | ||
| Class of Stock [Line Items] | ||
| Value of stock repurchased | $ 43.9 | $ 111.6 |
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Number of shares that have been repurchased and retired during the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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