Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 186,849	$ 217,027	$ 259,801	$ 185,123
Accounts receivable, net of allowance for doubtful accounts of $6,054 and $2,120, respectively	44,702	36,550
Other current assets	16,890	16,978
Total current assets	248,441	270,555
Property, plant and equipment, net	2,501,013	2,578,388
Deferred charges, net	12,812	19,077
Other assets	6,612	10,255
Total assets	2,768,878	2,878,275
Current liabilities:
Accounts payable	16,196	11,774
Accrued interest	14,734	14,763
Accrued payroll and benefits	9,475	8,596
Other accrued liabilities	8,457	10,010
Total current liabilities	48,862	45,143
Long-term debt, including deferred gain of $18,911 and $0, and net of original issue discount of $7,862 and $31,093 and deferred financing costs of $10,134 and $10,197, respectively	1,080,826	1,083,710
Deferred tax liabilities, net	197,465	343,020
Other liabilities	3,801	3,406
Total liabilities	1,330,954	1,475,279
Stockholders’ equity:
Preferred stock: $0.01 par value; 5,000 shares authorized; no shares issued and outstanding	0	0
Common stock: $0.01 par value; 100,000 shares authorized; 37,144 and 36,467 shares issued and outstanding, respectively	371	365
Additional paid-in capital	760,278	754,394
Retained earnings	668,598	637,992
Accumulated other comprehensive income	8,677	10,245
Total stockholders’ equity	1,437,924	1,402,996	$ 1,446,163	$ 1,370,765
Total liabilities and stockholders’ equity	$ 2,768,878	$ 2,878,275