| Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (Parenthetical) - $ / shares | 6 Months Ended | |
|---|---|---|
| Jun. 30, 2015 | Jun. 30, 2014 | |
| Class A Common Stock | ||
| Common stock dividends, per share | $ 0.24 | $ 0.24 | 
| X | ||||||||||
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- Definition Aggregate dividends paid during the period for each share of common stock outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Details 
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