| **Earnings per Share (Tables)**                                                                          | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
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| **Earnings Per Share [Abstract]**                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| Composition of Weighted-Average Common Shares (Denominator) Used in Basic and Diluted Earnings Per Share | The following table summarizes the composition of the weighted-average common shares (denominator) used in the basic and diluted earnings per share computations: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2016 2015 2016 2015Weighted average common shares issued105,563,455 105,563,455 105,563,455 105,563,455Average treasury stock shares(16,609,505) (16,602,502) (16,617,616) (15,858,433)Average unearned nonvested shares(99,502) (153,659) (103,696) (177,462)Weighted average common shares and common stock equivalents used to calculate basic earnings per share88,854,448 88,807,294 88,842,143 89,527,560Additional common stock equivalents (nonvested stock) used to calculate diluted earnings per share3,756 6,452 1,796 3,938Weighted average common shares and common stock equivalents used to calculate diluted earnings per share88,858,204 88,813,746 88,843,939 89,531,498 |
| Common Stock Equivalents Not Included in Computation of Diluted Earnings Per Share                       | The following table shows the number of shares and the price per share related to common stock equivalents that were not included in the computation of diluted earnings per share for the nine months endedSeptember 30 because to do so would have been antidilutive. 2016 2015   Price Range   Price Range Shares From To Shares From ToRestricted Stock72,432 $8.38 $10.09 121,091 $5.26 $9.84                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |

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| - Definition
Tabular disclosure of securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) in the future that were not included in the computation of diluted EPS because to do so would increase EPS amounts or decrease loss per share amounts for the period presented, by antidilutive securities.
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Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257
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| - Definition
Tabular disclosure of the weighted average number of shares used in calculating basic net earnings per share (or unit) and diluted earnings per share (or unit).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257
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