| **Accumulated Other Comprehensive Loss (Tables)**                                 | 12 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, for the year ended December 31, 2014 and 2013: Defined Benefit Pension Items Unrealized Gains and (Losses) on Available-for-Sale Securities TotalAccumulated other comprehensive loss at December 31, 2013$(5,392) $(2,125) $(7,517)Other comprehensive income before reclassifications(2,180) (509) (2,689)Amounts reclassified from accumulated other comprehensive loss7,572 1,309 8,881Net current year other comprehensive income (loss)5,392 800 6,192Accumulated other comprehensive loss at December 31, 2014$— $(1,325) $(1,325) Defined Benefit Pension Items Unrealized Gains and (Losses) on Available-for-Sale Securities TotalAccumulated other comprehensive loss at December 31, 2012$(8,652) $— $(8,652)Other comprehensive income before reclassifications2,191 (2,032) 159Amounts reclassified from accumulated other comprehensive loss1,069 (93) 976Net current year other comprehensive income (loss)3,260 (2,125) 1,135Accumulated other comprehensive loss at December 31, 2013$(5,392) $(2,125) $(7,517) |
| Reclassification out of Accumulated Other Comprehensive Income                    |   Amount Reclassified from Accumulated Other Comprehensive Loss  Details about Accumulated Other Comprehensive Loss Components 2014 2013 Affected Line in the Consolidated Statements of IncomeDefined Benefit Pension Items      Amortization of loss  $465 $326 Net periodic pension costs, Note 18, Employee Benefit PlansSettlement cost  7,107 743 Net periodic pension costs, Note 18, Employee Benefit PlansTotal before tax 7,572 1,069  Income tax benefit — —  Net of tax 7,572 1,069         Items related to available-for-sale securities      Other-than-temporary impairment losses 1,295 — Investment income, net, Note 6, InvestmentsRealized loss (gain) on sale 833 (93) Investment income, net, Note 6, InvestmentsTotal before tax 2,128 (93)  Income tax expense (819) —  Net of tax 1,309 (93)         Total reclassifications for the period $8,881 $976 Net of tax                                                                 |

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| - Definition
Tabular disclosure of information about items reclassified out of accumulated other comprehensive income (loss).
+ References
No definition available.
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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=36458714&loc=SL7669686-108580
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