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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
	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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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

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Number of options outstanding, including both vested and non-vested options.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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