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Fair Value Measurements - Additional Information (Detail) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2017 USD ($) Franchise Business | Sep. 30, 2016 Business | Jun. 30, 2016 Franchise | Jun. 30, 2017 Franchise Business | Jun. 30, 2016 Franchise
Business Acquisition [Line Items] |  |  |  |  |
Number of businesses acquired | Franchise | 0 |  | 0 | 0 | 0
Stand-alone Pre-owned Businesses and Real Estate [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Number of businesses acquired | Business |  | 3 |  |  |
Impairment of goodwill | $ | $ 0.9 |  |  |  |
Impairment of property and equipment | $ | $ 0.8 |  |  |  |
Number of businesses closed | Business | 2 |  |  | 2 |

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