Income Taxes (Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Reconciliation
Statutory federal rate	$ (40,732)	$ (149,310)	$ 15,026
Interest expense - preferred stock	20,459	0	0
State income taxes — net of federal benefit	(1,465)	(5,368)	1,294
Gain on sale of Unitrans	(1,161)	0	0
Goodwill impairment	1,020	86,776	0
Effect of change in U.S. statutory income tax rate	(7,413)	0	0
Change in valuation allowance	1,989	1,624	99
Other	2,112	(3)	893
Total	$ (25,191)	$ (66,281)	$ 17,312