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Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2017
Income Taxes [Line Items]    
Unrecognized Tax Benefits, Decreases Resulting from Settlements with Taxing Authorities, Portion Which Affected Effective Tax Rate $ 19,500  
Deferred Tax Assets and Liabilities [Abstract]    
Non-current deferred tax liability 81,454 $ 86,657
Net deferred tax liability 81,454 86,657
Deferred tax assets    
Federal net operating loss carryforwards 201,978 110,350
State net operating loss carryforwards 38,715 45,096
Share-based compensation 26,344 14,226
Other 63,815 35,161
Gross deferred tax assets 330,852 204,833
Valuation allowance (28,402) (28,821)
Deferred tax assets, net of valuation allowance 302,450 176,012
Deferred tax liabilities    
Difference between book and tax basis of property and intangible assets 337,654 219,090
State tax liability 31,443 33,777
Other 14,807 9,802
Gross deferred tax liabilities 383,904 262,669
State and Local Jurisdiction    
Deferred tax assets    
Federal net operating loss carryforwards   732,400
All years [Member]    
Income Taxes [Line Items]    
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities $ 27,700  
Alternative Minimum Tax Credit Carryforward [Member] | Internal Revenue Service (IRS)    
Income Taxes [Line Items]    
Tax credit carryforwards   $ 10,400