Annual report pursuant to Section 13 and 15(d)

Income Taxes (Deferred Tax Assets and Liabilities) (Details)

v3.8.0.1
Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Deferred tax assets:    
Net operating loss carryforwards $ 104,617 $ 111,236
Deferred revenue for financial reporting purposes 44,853 59,993
Asset retirement obligations in excess of amounts recognized for tax purposes 13,328 16,808
Compensated absences accrued for financial reporting purposes 2,825 3,505
Share-based compensation expense for financial reporting purposes in excess of amounts recognized for tax purposes 2,629 3,393
Accounts receivable, principally due to allowance for doubtful receivables 1,023 1,965
Workers compensation and self-insurance health reserves, principally due to accrual for financial reporting purposes 1,523 1,705
Alternative minimum tax credits 1,735 1,735
Deferred compensation expense for tax purposes in excess of amounts recognized for financial reporting purposes 1,370 1,687
Other 5,671 11,515
Total deferred tax assets 179,574 213,542
Deferred tax liabilities:    
Plant and equipment, principally due to differences in depreciation 192,413 245,118
Intangible assets 77,455 106,061
Other 277 345
Total deferred tax liabilities 270,145 351,524
Net deferred tax liabilities $ 90,571 $ 137,982