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Stockholders' Equity - Narrative (Details) |  |  |  |  |  |  |  |  |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |  |
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Jan. 24, 2017 USD ($) shares | Apr. 08, 2016 USD ($) shares | Oct. 30, 2015 USD ($) shares | Aug. 04, 2015 USD ($) shares | Aug. 03, 2015 USD ($) | May 13, 2015 USD ($) shares | May 04, 2015 USD ($) | Feb. 11, 2015 shares | Jan. 22, 2015 USD ($) shares | Jan. 20, 2015 shares | Mar. 31, 2017 class | Mar. 31, 2016 USD ($) | Sep. 30, 2017 $ / shares | Dec. 31, 2017 USD ($) $ / shares shares | Dec. 31, 2016 USD ($) $ / shares shares | Dec. 31, 2015 USD ($) $ / shares shares | Apr. 07, 2016 shares | Jan. 12, 2016 USD ($) | Jul. 28, 2015 USD ($) | Dec. 31, 2014 $ / shares shares | Aug. 13, 2012 shares
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 23,984 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 23,984 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1.37 |  |  |  |  |
Number of classes of stock | class |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |
Preferred stock, shares authorized |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,000,000 | 5,000,000 |  |  |  |  |  |
Preferred stock, par value (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.001 | $ 0.001 |  |  |  |  |  |
Common stock, shares authorized |  |  |  |  |  |  |  |  |  |  |  |  |  | 50,000,000 | 50,000,000 |  |  |  |  |  |
Common stock, par value (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.001 | $ 0.001 |  |  |  |  |  |
Authorized amount of shares to be repurchased | $ |  |  |  |  |  |  | $ 5,000,000.0 |  |  |  |  |  |  |  |  |  |  | $ 70,000,000.0 | $ 15,000,000.0 |  |
Treasury stock, purchase price | $ |  |  | $ 3,600,000 |  | $ 3,500,000 |  | $ 3,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of common stock (in shares) |  |  | 106,264 | 162,442 |  | 186,519 |  |  |  |  |  |  |  |  | 903,031 |  |  |  |  |  |
Repurchase of common stock | $ |  |  | $ 5,000,000.0 | $ 5,000,000.0 |  | $ 5,000,000.0 |  |  |  |  |  |  |  |  | $ 23,704,000 | $ 16,071,000 |  |  |  |  |
Remaining authorized repurchase amount | $ |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 32,000,000.0 |  |  |  |  |  |  |
Number of shares authorized to be repurchased |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 100,000
Allocated Share-based Compensation Expense | $ |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 35,000 | $ 104,000 | $ 86,000 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost | $ |  |  |  |  |  |  |  |  |  |  |  | $ 64,000 |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,393,873 |  |  |  |  |  |  |
Stock Issued During Period, Value, Restricted Stock Award, Gross | $ | $ 1,400,000 | $ 1,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 |  |  |  | $ 1.37 |
George K. Broady |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of common stock (in shares) |  |  |  |  |  |  |  |  | 91,817 |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of common stock | $ |  |  |  |  |  |  |  |  | $ 1,100,000 |  |  |  |  |  |  |  |  |  |  |  |
Shares repurchased per trading day |  |  |  |  |  |  |  |  | 5,000 |  |  |  |  |  |  |  |  |  |  |  |
Restricted Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 | 22,348 | 44,712 |  |  |  | 0 |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12.15 | $ 12.15 | $ 0 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12.15 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | 56,260 | 51,015 |  |  |  |  |  | 6,116 |  | 60,960 |  |  |  |  |  | 67,076 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period |  |  |  |  |  |  |  |  |  |  |  |  |  | (21,930) | (22,364) | (22,364) |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  | $ 12.15 | $ 12.15 | $ 12.15 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period |  |  |  |  |  |  |  |  |  |  |  |  |  | (418) |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12.28 |  |  |  |  |  |  |
Equity Incentive 2016 Plan [Member] | Restricted Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number |  |  |  |  |  |  |  |  |  |  |  |  |  | 58,032 | 38,256 | 0 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 28.72 | $ 34.13 | $ 0 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 25.44 | $ 34.13 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period |  |  |  |  |  |  |  |  |  |  |  |  |  | 56,260 | 51,015 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period |  |  |  |  |  |  |  |  |  |  |  |  |  | (35,336) | (12,759) |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 29.58 | $ 34.13 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period |  |  |  |  |  |  |  |  |  |  |  |  |  | (1,148) |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 28.55 |  |  |  |  |  |  |
Common Stock | Equity Incentive 2016 Plan [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,500,000 |  |  |  |

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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units. + 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)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + 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)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement. + 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)(2)(iii)(2) -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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