| **Accumulated Other Comprehensive Loss (Tables)**                                 | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                         |
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| **Stockholders' Equity Note [Abstract]**                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| Summary of Changes in Accumulated Other Comprehensive Loss for Pension Plan Items | Following is a summary of the changes in the accumulated balances for each component of accumulated other comprehensive loss, which is presented net of tax, as of June 30, 2016: Unrealized Gains on Available-for-Sale Securities TotalAccumulated other comprehensive loss at December 31, 2015$(686) $(686)Other comprehensive income1 1Accumulated other comprehensive loss at June 30, 2016$(685)$(685) |

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| - Definition
Tabular disclosure of the components of accumulated other comprehensive income (loss).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669686-108580
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| - References
No definition available.
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