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Stockholders' Equity Stockholders' Equity (Tables) | 12 Months Ended
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Dec. 31, 2017
Stockholders' Equity Attributable to Parent [Abstract] |
QuarterlydividendsdeclaredTableTextBlock [Table Text Block] | Dividends The Board declared quarterly dividends in 2017 and 2016 as follows:
|  | 2017 |  | 2016 |
|  | (amounts per share) |
First quarter |  | $ | 0.125 |  |  | $ | 0.110 |  |
Second quarter |  | 0.150 |  |  | 0.125 |  |
Third quarter |  | 0.150 |  |  | 0.125 |  |
Fourth quarter |  | 1.150 |  | (1) | 0.125 |  |
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(1) | Includes a $1.00 per share special dividend.

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- Definition Tabular disclosure of all or some of the information related to dividends declared and paid as of the financial reporting date. + References No definition available. + Details
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- References No definition available. + Details
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