| **Property and Equipment - Straight-line Rental Accrual (Details) - USD ($) $ in Millions** | Dec. 31, 2016 | Dec. 31, 2015 |
|---------------------------------------------------------------------------------------------|---------------|---------------|
| **Property, Plant and Equipment [Abstract]**                                                |          |          |
| Straight-line rental accrual                                                                | $ 11.8        | $ 12.4        |

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| - Definition
For a classified balance sheet, the cumulative difference between the rental income or payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense, by the lessor or lessee, respectively, more than one year after the balance sheet date.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.26(c)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 25 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7501430&loc=d3e39927-112707
+ Details**Name:**us-gaap_DeferredRentCreditNoncurrent**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
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| - References
No definition available.
+ Details**Name:**us-gaap_PropertyPlantAndEquipmentAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |