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Shareholders' Equity (Cash Dividends Declared) (Details) - $ / shares | 3 Months Ended | 12 Months Ended
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Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash dividends declared per common share (USD per share) | $ 1.31 | $ 0.31 | $ 0.31 | $ 0.31 | $ 2.96 | $ 0.30 | $ 0.30 | $ 0.3 | $ 0.3 | $ 0.25 | $ 0.25 | $ 0.25 | $ 2.24 | $ 3.86 | $ 1.05
Dividends Declared, Special [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash dividends declared per common share (USD per share) | $ 1 |  |  |  | $ 2.65 |  |  |  |  |  |  |  |  |  |

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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. + References No definition available. + Details
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- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
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