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2012 Incentive Compensation Plan - Additional Information (Detail) - USD ($) |  |  |  | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Jul. 06, 2015 | Jun. 06, 2012 | Apr. 29, 2011 | Sep. 30, 2015 | Sep. 30, 2014 | Sep. 30, 2015 | Sep. 30, 2014 | Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Number of shares granted under SAR Award Agreement |  | 543,872 |  |  |  |  |  |
Common stock, market value per share |  |  |  | $ 22.07 |  | $ 22.07 |  |
Valuation dates of common stock under SAR award agreement, description |  |  |  |  |  | Commenced after the SAR Grant Date and prior to the expiration date |  |
SAR award expiration period from grant date |  |  |  |  |  | 10 years |  |
Expected term |  |  |  |  |  | 6 years |  |
Risk-free interest rate |  |  |  |  |  | 0.92% |  |
Dividend yield |  |  |  |  |  | $ 0 |  |
Anticipated volatility factor and zero dividend yield |  |  | 50.00% |  |  | 55.00% |  |
Discount on valuation of trading activity |  |  |  | 15.00% |  | 15.00% |  |
Service period |  |  |  |  |  | 1 year 9 months 11 days |  |
Expenses for the SAR granted |  |  |  | $ 41,000 | $ 51,000 | $ 127,000 | $ 279,000 |
Total unrecognized compensation expense |  |  |  | $ 333,000 |  | 333,000 |  |
Total expected expense from initial grant |  |  |  |  |  | $ 2,133,000 |  |
Expected period of recognition of cost |  |  |  |  |  | 4 years |  |
Employee Stock Option 2012 [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Restricted stock agreement vesting |  |  |  |  |  | These shares of Restricted Stock vest in various increments and periods over a maximum of ten years from the date the stock was granted as defined under the applicable Restricted Stock Award Agreement. |  |
Minimum [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Expected term to exceed public equivalent value over aggregate exercise price |  |  |  |  |  | $ 22.07 |  |
SAR [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Fair value of SAR granted |  |  |  |  |  | $ 3.31 |  |
SAR [Member] | Chief Operating Officer [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Number of shares granted to employees |  | 543,872 |  |  |  |  |  |
Stock Compensation Plan [Member] | 2012 Plan [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Shares authorized for stock-based compensation |  |  |  | 1,530,925 |  | 1,530,925 |  |
Common stock available for further issuance |  |  |  | 800,060 |  | 800,060 |  |
Restricted Stock [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Number of shares granted to employees |  |  |  |  |  | 186,993 |  |
Fair value of SAR granted |  |  |  |  |  | $ 28.48 |  |
Unvested portion of the company's common stock |  |  |  | 134,904 |  | 134,904 |  | 154,251
Number of vesting shares |  |  |  |  |  | 19,547 |  |
Expected period of recognition of cost |  |  |  |  |  | 6 years |  |
Compensation expenses |  |  |  | $ 236,000 | $ 268,000 | $ 727,000 | $ 703,000 |
Restricted Stock [Member] | 2012 Plan [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Total unrecognized compensation expense |  |  |  | $ 5,144,000 |  | $ 5,144,000 |  |
Restricted Stock [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Vesting period for restricted stock |  |  |  |  |  | 10 years |  |
SAR Award Agreement Amended [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Unvested portion of the company's common stock | 181,290 |  |  |  |  |  |  |
Deferred vesting period | 30 days |  |  |  |  |  |  |
SAR Award Agreement Amended [Member] | Tranche One [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Number of vesting shares | 100,000 |  |  |  |  |  |  |
SAR Award Agreement Amended [Member] | Tranche Two [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Number of vesting shares | 81,290 |  |  |  |  |  |  |
SAR Award Agreement Amended [Member] | Deferred Bonus Granted in 2016 [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Amount of annual bonus | $ 250,000 |  |  |  |  |  |  |
SAR Award Agreement Amended [Member] | Deferred Bonus Granted in 2017 [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Amount of annual bonus | 250,000 |  |  |  |  |  |  |
SAR Award Agreement Amended [Member] | Deferred Bonus Granted in 2018 [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Amount of annual bonus | 250,000 |  |  |  |  |  |  |
SAR Award Agreement Amended [Member] | Deferred Bonus Granted in 2019 [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Amount of annual bonus | $ 250,000 |  |  |  |  |  |  |

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