|**Properties and Equipment Assets held-for-sale (Tables)**                                                                        | 12 Months Ended                                                                                                                                                                   
|--------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|
|**Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]** |                                                                                                                                                                                   
|Disclosure of Long Lived Assets Held-for-sale [Table Text Block]                                                                  | December 31, 2018(in thousands)AssetsProperties and equipment, net$137,448Other assets3,257Total assets$140,705LiabilitiesAsset retirement obligation$4,111Total liabilities$4,111
|                                                                                                                                 
|                                                                                                                                  |                                                                                                                                                                                   
|                                                                                                                                  | December 31, 2018                                                                                                                                                                 
|                                                                                                                                  | (in thousands)                                                                                                                                                                    
|Assets                                                                                                                            |                                                                                                                                                                                   
|Properties and equipment, net                                                                                                     | $                                                                                                                                                                                 
|Other assets                                                                                                                      | 3,257                                                                                                                                                                             
|Total assets                                                                                                                      | $                                                                                                                                                                                 
|                                                                                                                                  |                                                                                                                                                                                   
|Liabilities                                                                                                                       |                                                                                                                                                                                   
|Asset retirement obligation                                                                                                       | $                                                                                                                                                                                 
|Total liabilities                                                                                                                 | $                                                                                                                                                                                 

X- DefinitionTabular disclosure of long lived assets held for sale. Disclosure may include the description of the facts and circumstances leading to the expected disposal, manner and timing of disposal, the carrying value of the assets held for sale, the gain (loss) recognized in the income statement and the income statement caption that includes that gain (loss).
+ ReferencesReference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230
+ Details**Name:**
us-gaap_DisclosureOfLongLivedAssetsHeldForSaleTextBlock**Namespace Prefix:**
us-gaap_**Data Type:**
nonnum:textBlockItemType**Balance Type:**
na**Period Type:**
duration X- DefinitionLine 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.
+ ReferencesNo definition available.
+ Details**Name:**
us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems**Namespace Prefix:**
us-gaap_**Data Type:**
xbrli:stringItemType**Balance Type:**
na**Period Type:**
duration