Schedule I - Parent Only - Condensed Statement of Operations (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Equity in income									$ (19.9)	$ 20.4	$ 18.9
Revenues	$ 1,224.9	$ 1,104.6	$ 1,033.2	$ 889.7	$ 1,066.5	$ 1,170.6	$ 1,274.5	$ 940.5	4,252.4	4,452.1	3,507.8
General and administrative									122.5	136.9	97.3
Impairments				873.3	764.2	799.2			873.3	1,563.4
Total operating costs and expenses									4,926.9	5,754.0	3,153.5
Operating income (loss)	$ 39.2	$ 65.9	$ 45.2	$ (824.8)	$ (692.0)	$ (731.8)	$ 71.4	$ 50.5	(674.5)	(1,301.9)	354.3
Income (loss) before non-controlling interest and income taxes									(883.6)	(1,384.0)	326.1
Income tax provision									(4.6)	(25.7)	(76.4)
Net income (loss)									$ (888.2)	$ (1,409.7)	$ 250.7
Basic common unit	$ (0.02)		$ 0.01	$ (2.56)	$ (1.18)	$ (1.18)	$ 0.09	$ 0.10	$ (2.56)	$ (2.17)	$ 0.55
Diluted common unit	$ (0.02)		$ 0.01	$ (2.56)	$ (1.18)	$ (1.18)	$ 0.09	$ 0.10	$ (2.56)	$ (2.17)	$ 0.55
Weighted average common shares outstanding: Basic (usd per share)									179.7	164.2	164.0
Weighted average common shares outstanding: diluted (in units)									179.7	164.2	164.3
Parent Company
Condensed Financial Statements, Captions [Line Items]
Equity in income									$ (145.1)	$ (325.5)	$ 185.7
Revenues									(145.1)	(325.5)	185.7
General and administrative									3.1	4.5	3.0
Impairments									307.0
Total operating costs and expenses									310.1	4.5	3.0
Operating income (loss)									(455.2)	(330.0)	182.7
Interest and other expense									(1.4)	(0.8)	(2.4)
Income (loss) before non-controlling interest and income taxes									(456.6)	(330.8)	180.3
Income tax provision									(3.4)	(26.2)	(54.3)
Net income (loss)									$ (460.0)	$ (357.0)	$ 126.0
Basic common unit									$ (2.56)	$ (2.17)	$ 0.55
Diluted common unit									$ (2.56)	$ (2.17)	$ 0.55
Weighted average common shares outstanding: Basic (usd per share)									179.7	164.2	164.0
Weighted average common shares outstanding: diluted (in units)									179.7	164.2	164.3