Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
REVENUES	$ 463,331	$ 459,295	$ 910,716	$ 885,295
EXPENSES:
Operating	316,446	318,035	630,364	618,697
General and administrative	27,364	23,107	53,844	49,979
Depreciation and amortization	42,345	38,400	84,404	67,085
Asset impairments				955
Costs and Expenses, Total	386,155	379,542	768,612	736,716
OPERATING INCOME	77,176	79,753	142,104	148,579
OTHER EXPENSE:
Interest expense, net	16,796	11,761	34,340	21,951
Other expense	132	36	49	10
Total non-operating expense (income)	16,928	11,797	34,389	21,961
INCOME BEFORE INCOME TAXES	60,248	67,956	107,715	126,618
Income tax expense	(2,665)	(2,653)	(3,825)	(4,038)
NET INCOME	$ 57,583	$ 65,303	$ 103,890	$ 122,580
BASIC EARNINGS PER SHARE	$ 0.49	$ 0.56	$ 0.89	$ 1.05
DILUTED EARNINGS PER SHARE	0.49	0.55	0.88	1.04
DIVIDENDS DECLARED PER SHARE	$ 0.54	$ 0.54	$ 1.08	$ 1.08