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Stock-based Compensation: Incentive Award Plan and Employee Stock Purchase Plan Stock-based Compensation: Incentive Award Plan and Employee Stock Purchase Plan (Range of Prices) (Details) - $ / shares | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price, low end of the range (in dollars per share) | $ 4.44 |
Exercise price, high end of the range (in dollars per share) | $ 16.51 |
Options outstanding (in shares) | 169,919 |
Options outstanding - weighted average remaining contractual life (years) | 4 years 3 months | 3 years 6 months
Options outstanding - weighted average exercise price (in dollars per share) | $ 12.10 | $ 12.11
Options exercisable - at the end of period (in shares) | 169,919 |
Options exercisable - weighted average exercise price (in dollars per share) | $ 12.10 |
$4.44 - 7.31 |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price, low end of the range (in dollars per share) | 4.44 |
Exercise price, high end of the range (in dollars per share) | $ 7.31 |
Options outstanding (in shares) | 34,149 |
Options outstanding - weighted average remaining contractual life (years) | 2 years 4 months 24 days |
Options outstanding - weighted average exercise price (in dollars per share) | $ 6.17 |
Options exercisable - at the end of period (in shares) | 34,149 |
Options exercisable - weighted average exercise price (in dollars per share) | $ 6.17 |
$7.39 - 10.46 |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price, low end of the range (in dollars per share) | 7.39 |
Exercise price, high end of the range (in dollars per share) | $ 10.46 |
Options outstanding (in shares) | 49,020 |
Options outstanding - weighted average remaining contractual life (years) | 4 years 1 month 6 days |
Options outstanding - weighted average exercise price (in dollars per share) | $ 9.18 |
Options exercisable - at the end of period (in shares) | 49,020 |
Options exercisable - weighted average exercise price (in dollars per share) | $ 9.18 |
$13.31 - 13.31 |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price, low end of the range (in dollars per share) | 13.31 |
Exercise price, high end of the range (in dollars per share) | $ 13.31 |
Options outstanding (in shares) | 10,250 |
Options outstanding - weighted average remaining contractual life (years) | 1 month 1 day |
Options outstanding - weighted average exercise price (in dollars per share) | $ 13.31 |
Options exercisable - at the end of period (in shares) | 10,250 |
Options exercisable - weighted average exercise price (in dollars per share) | $ 13.31 |
$13.58 - 13.58 |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price, low end of the range (in dollars per share) | 13.58 |
Exercise price, high end of the range (in dollars per share) | $ 13.58 |
Options outstanding (in shares) | 1,500 |
Options outstanding - weighted average remaining contractual life (years) | 5 years 2 months 12 days |
Options outstanding - weighted average exercise price (in dollars per share) | $ 13.58 |
Options exercisable - at the end of period (in shares) | 1,500 |
Options exercisable - weighted average exercise price (in dollars per share) | $ 13.58 |
$16.51 - 16.51 |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price, low end of the range (in dollars per share) | 16.51 |
Exercise price, high end of the range (in dollars per share) | $ 16.51 |
Options outstanding (in shares) | 75,000 |
Options outstanding - weighted average remaining contractual life (years) | 5 years 8 months 12 days |
Options outstanding - weighted average exercise price (in dollars per share) | $ 16.51 |
Options exercisable - at the end of period (in shares) | 75,000 |
Options exercisable - weighted average exercise price (in dollars per share) | $ 16.51 |

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- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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