Stock-based Compensation Plans and Awards - Stock-based compensation expense narrative (Details) - USD ($) $ in Millions |
12 Months Ended | |
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Dec. 31, 2017 |
Dec. 31, 2016 |
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| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | ||
| Capitalized cost related to internal use software and website development costs | $ 7.4 | $ 7.5 |
| General and administrative | ||
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||
| Accelerated awards in connection with executive severance | $ 5.4 | $ 8.7 |
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- Definition The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- References No definition available.
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Additional share-based compensation cost recognized as a result of an occurrence of an event that accelerates its recognition. No definition available.
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- Details
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