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Stock-Based Compensation - Narrative (Details) |  |  |  |  | 1 Months Ended | 12 Months Ended |
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Aug. 31, 2016 USD ($) shares | Aug. 23, 2016 USD ($) $ / shares shares | Feb. 29, 2016 USD ($) shares | Jan. 01, 2016 shares | May 31, 2015 shares | Jun. 30, 2014 shares | Jun. 30, 2010 USD ($) item shares | Dec. 31, 2016 USD ($) $ / shares shares | Dec. 31, 2015 USD ($) $ / shares shares | Dec. 31, 2014 USD ($) $ / shares shares | Dec. 31, 2013 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Options expired in relation to the Offer |  | 456,995 |  |  |  |  |  |  |  |  |
Shares issued in Replacement Offering |  | 334,027 |  |  |  |  |  |  |  |  |
Shares eligible for purchase via options |  | 113,531 |  |  |  |  |  |  |  |  |
Weighted-average exercise price (in dollars per share) | $ / shares |  | $ 7.20 |  |  |  |  |  |  |  |  |
Vesting period of replacement options |  | 3 years |  |  |  |  |  |  |  |  |
Incremental charge resulting from the plan modification | $ |  | $ 926,000 |  |  |  |  |  |  |  |  |
Amortization period of incremental charge |  | 3 years |  |  |  |  |  |  |  |  |
Options |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Unamortized compensation cost, net of expected forfeitures | $ |  |  |  |  |  |  |  | $ 2,600,000 |  |  |
Weighted average expected period over which the expense is to be recognized |  |  |  |  |  |  |  | 2 years 7 months 6 days |  |  |
Fair value of vested options and awards | $ |  |  |  |  |  |  |  | $ 2,000,000 |  |  |
Tax benefits associated with exercise of stock options | $ |  |  |  |  |  |  |  | 0 | $ 0 | $ 0 |
Intrinsic value of awards exercised | $ |  |  |  |  |  |  |  | 0 | $ 300,000 | $ 800,000 |
RSU's |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Unamortized compensation cost, net of expected forfeitures | $ |  |  |  |  |  |  |  | $ 600,000 |  |  |
Weighted average expected period over which the expense is to be recognized |  |  |  |  |  |  |  | 2 years |  |  |
Employee stock purchase plan |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Number of shares reserved for issuance |  |  |  |  |  |  | 200,000 |  |  |  |
Increase in number of shares reserved for issuance |  |  |  |  | 200,000 |  |  |  |  |  |
Number of offering periods | item |  |  |  |  |  |  | 2 |  |  |  |
Offering period |  |  |  |  |  |  | 6 months |  |  |  |
Purchase price to be paid by participants as a percentage of price per share either at the beginning or the end of each six-month offering period, whichever is less |  |  |  |  |  |  | 85.00% |  |  |  |
Shares of common stock issued under the plan | 31,900 |  | 37,300 |  |  |  |  |  |  |  |
Aggregate purchase price of shares issued | $ | $ 167,000 |  | $ 197,000 |  |  |  |  |  |  |  |
Shares authorized and unissued |  |  |  |  |  |  |  | 150,000 |  |  |
Employee stock purchase plan | Maximum |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Maximum amount of shares that eligible employee may purchase annually (in dollars) | $ |  |  |  |  |  |  | $ 25,000 |  |  |  |
Inducement Stock Options |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Stock options exercised |  |  |  |  |  |  |  |  | 52,000 | 7,000 |
Weighted-average exercise price (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  | $ 43.74 | $ 36.78 | $ 44.23
Number of shares outstanding |  |  |  |  |  |  |  |  | 164,000 | 223,000 | 318,000
Equity Incentive Plan2010 [Member] |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Term of Plan |  |  |  |  |  |  |  | 10 years |  |  |
Number of shares reserved for issuance |  |  |  |  |  |  |  |  | 400,000 |  |
Increase in number of shares reserved for issuance |  |  |  | 50,000 |  |  |  |  |  |  |
Equity Incentive Plan2010 [Member] | Options |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Maximum annual option grants or other awards to the entity's non-employee directors (in shares) |  |  |  |  |  |  |  | 4,000 |  |  |
Maximum one-time grant of an option or other awards to the entitiy's non employee directors (in shares) |  |  |  |  |  |  |  | 12,000 |  |  |
Maximum term of options granted |  |  |  |  |  |  |  | 10 years |  |  |
Minimum percentage of voting rights required for applicability of a specific expriation term |  |  |  |  |  |  |  | 10.00% |  |  |
Maximum expiration term of options granted |  |  |  |  |  |  |  | 5 years |  |  |
Vesting period of replacement options |  |  |  |  |  |  |  | 4 years |  |  |
Increase in number of shares reserved for issuance |  |  |  |  |  | 150,000 |  | 50,000 | 50,000 | 200,000 |
Equity Incentive Plan2010 [Member] | Options | Minimum |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Term of Plan |  |  |  |  |  |  |  | 6 years |  |  |
Equity Incentive Plan2010 [Member] | Options | Maximum |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Term of Plan |  |  |  |  |  |  |  | 10 years |  |  |
Amended 2000 Plan [Member] |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Shares authorized and unissued |  |  |  |  |  |  |  | 0 |  |  |
Mosy Plans [Member] | Options |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Stock options exercised |  |  |  |  |  |  |  |  | 8,000 | 41,000 |
Options expired in relation to the Offer |  |  |  |  |  |  |  | 58,000 |  |  |
Shares issued in Replacement Offering |  |  |  |  |  |  |  | 384,000 | 154,000 | 17,000 |
Weighted-average exercise price (in dollars per share) | $ / shares |  |  |  |  |  |  |  | $ 13.88 | $ 35.14 | $ 38.73 | $ 38.64
Shares authorized and unissued |  |  |  |  |  |  |  | 114,000 | 106,000 | 176,000 | 42,000
Number of shares outstanding |  |  |  |  |  |  |  | 522,000 | 675,000 | 599,000 | 672,000
Mosy Plans [Member] | RSU's |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] |  |  |  |  |  |  |  |  |  |  |
Total intrinsic value of the restricted stock units outstanding | $ |  |  |  |  |  |  |  | $ 300,000 |  |  |

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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + 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 (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + 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 (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements. + 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)(iv)(4) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock 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)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition An excess of the fair value of the modified award over the fair value of the award immediately before the modification. + 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 (h)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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