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Financial Instruments and Fair Value Measurements (Narrative) (Details) - USD ($) | 4 Months Ended | 12 Months Ended
--- | --- | ---
Apr. 30, 2015 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Franchise rights impairment |  | $ 0 | $ 15,400,000 | $ 0
Nonrecurring [Member] |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Goodwill impairment |  | 0 | 0 |
Impairment of long-lived assets for sale |  | $ 12,800,000 | $ 3,800,000 |
Goodwill [Member] |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Date of annual goodwill and indefinite lived intangible assets impairment test |  | April 30 | April 30 |
Franchise Rights [Member] |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Date of annual goodwill and indefinite lived intangible assets impairment test |  | April 30 | April 30 |
Franchise Rights [Member] | Nonrecurring [Member] |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Franchise rights impairment | $ 0 | $ 0 |  |
Franchise Rights [Member] | Nonrecurring [Member] | Volkswagen [Member] |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Franchise rights impairment |  | 0 | $ 15,400,000 |
Continuing Operations [Member] | Nonrecurring [Member] |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Impairment of long-lived assets held and used |  | 1,900,000 | 3,100,000 |
Impairment of long-lived assets for sale |  | 12,100,000 | 3,000,000 |
Discontinued Operations, Held-for-sale [Member] | Nonrecurring [Member] |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Impairment of long-lived assets for sale |  | 700,000 | 800,000 |
Reported Value Measurement [Member] | Continuing Operations [Member] |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Long-lived assets held for sale |  | 41,400,000 | 47,100,000 |
Reported Value Measurement [Member] | Discontinued Operations, Held-for-sale [Member] |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Long-lived assets held for sale |  | $ 15,700,000 | $ 22,300,000 |

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