CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
REVENUES	$ 379.4	$ 545.4	$ 1,491.4	$ 1,601.2
COSTS AND EXPENSES:
Direct operating costs (excluding items below)	186.0	247.6	598.3	757.3
Depreciation and amortization	102.2	104.1	301.2	289.2
Selling, general and administrative	23.5	29.7	76.5	88.4
Loss on disposals of property and equipment	1.2	2.3	5.3	2.1
Material charges and other operating items	32.9	332.3	32.9	337.3
Total costs and expenses	345.8	716.0	1,014.2	1,474.3
Income (loss) from operations	33.6	(170.6)	477.2	126.9
OTHER INCOME (EXPENSE):
Interest expense, net of interest capitalized	(39.4)	(41.3)	(116.6)	(104.9)
Gain on extinguishment of debt	0.0	0.0	2.4	0.0
Interest income	1.2	0.2	2.1	0.8
Other - net	(2.1)	(1.8)	(5.4)	(2.9)
Total other income (expense), net	(40.3)	(42.9)	(117.5)	(107.0)
INCOME (LOSS) BEFORE INCOME TAXES	(6.7)	(213.5)	359.7	19.9
Provision (benefit) for income taxes	(12.2)	25.9	14.7	50.9
NET INCOME (LOSS)	$ 5.5	$ (239.4)	$ 345.0	$ (31.0)
NET INCOME (LOSS) PER SHARE - BASIC (in dollars per share)	$ 0.04	$ (1.92)	$ 2.75	$ (0.25)
NET INCOME (LOSS) PER SHARE - DILUTED (in dollars per share)	0.04	(1.92)	2.73	(0.25)
CASH DIVIDENDS DECLARED PER SHARE (in dollars per share)	$ 0	$ 0.1	$ 0	$ 0.30