Supplemental Guarantor/Non-Guarantor Financial Information Supplemental Guarantor/Non-Guarantor Financial Information (Details 3) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net (loss) income	$ (470.2)	$ (301.9)	$ (1,043.5)	$ (173.3)	$ (513.0)	$ (149.0)	$ (71.2)	$ (44.1)	$ (1,988.9)	$ (777.3)	$ (512.6)
Unrealized holding losses on available-for-sale securities									0.0	(3.7)	(12.3)
Reclassification for realized losses included in net (loss) income									0.0	2.9	12.8
Net change in unrealized (losses) gains on available-for-sale securities									0.0	(0.8)	0.5
Decrease in fair value of cash flow hedges									(131.3)	(195.0)	(333.6)
Reclassification for realized losses (gains) included in net loss									251.7	(10.2)	(209.6)
Net unrealized gains (losses) on cash flow hedges									120.4	(205.2)	(543.2)
Prior service credit (cost) for the period									10.4	11.4	(1.4)
Net actuarial gain (loss) for the period									18.1	(142.7)	110.9
Amortization of actuarial loss and prior service cost included in net (loss) income									31.9	32.7	95.7
Postretirement plans and workers' compensation obligations									60.4	(98.6)	205.2
Foreign currency translation adjustment									(34.9)	(41.0)	(92.7)
Other comprehensive loss from investment in subsidiaries									0.0	0.0	0.0
Other comprehensive income (loss), net of income taxes									145.9	(345.6)	(430.2)
Comprehensive loss									(1,843.0)	(1,122.9)	(942.8)
Less: Comprehensive income attributable to noncontrolling interests									7.1	9.7	12.3
Comprehensive loss attributable to common stockholders									(1,850.1)	(1,132.6)	(955.1)
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									(1,996.0)	(787.0)	(524.9)
Unrealized holding losses on available-for-sale securities										(3.7)	(12.2)
Reclassification for realized losses included in net (loss) income										2.9	13.0
Net change in unrealized (losses) gains on available-for-sale securities									0.0	(0.8)	0.8
Decrease in fair value of cash flow hedges									(137.1)	(225.9)	(368.4)
Reclassification for realized losses (gains) included in net loss									292.1	31.3	(109.0)
Net unrealized gains (losses) on cash flow hedges									155.0	(194.6)	(477.4)
Prior service credit (cost) for the period									0.0	0.0	0.0
Net actuarial gain (loss) for the period									5.5	0.0	0.0
Amortization of actuarial loss and prior service cost included in net (loss) income									7.2	0.0	0.0
Postretirement plans and workers' compensation obligations									12.7	0.0	0.0
Foreign currency translation adjustment									0.0	0.0	0.0
Other comprehensive loss from investment in subsidiaries									(21.8)	(150.2)	46.4
Other comprehensive income (loss), net of income taxes									145.9	(345.6)	(430.2)
Comprehensive loss									(1,850.1)	(1,132.6)	(955.1)
Less: Comprehensive income attributable to noncontrolling interests									0.0	0.0	0.0
Comprehensive loss attributable to common stockholders									(1,850.1)	(1,132.6)	(955.1)
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									209.0	137.7	345.4
Unrealized holding losses on available-for-sale securities										0.0	0.0
Reclassification for realized losses included in net (loss) income										0.0	0.0
Net change in unrealized (losses) gains on available-for-sale securities									0.0	0.0	0.0
Decrease in fair value of cash flow hedges									0.0	0.0	0.0
Reclassification for realized losses (gains) included in net loss									0.0	0.0	0.0
Net unrealized gains (losses) on cash flow hedges									0.0	0.0	0.0
Prior service credit (cost) for the period									10.4	11.4	(1.4)
Net actuarial gain (loss) for the period									12.6	(150.2)	103.8
Amortization of actuarial loss and prior service cost included in net (loss) income									36.6	35.5	95.8
Postretirement plans and workers' compensation obligations									59.6	(103.3)	198.2
Foreign currency translation adjustment									0.0	0.0	0.0
Other comprehensive loss from investment in subsidiaries									0.0	0.0	0.0
Other comprehensive income (loss), net of income taxes									59.6	(103.3)	198.2
Comprehensive loss									268.6	34.4	543.6
Less: Comprehensive income attributable to noncontrolling interests									0.0	0.0	0.0
Comprehensive loss attributable to common stockholders									268.6	34.4	543.6
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									(1,135.8)	(559.1)	(605.6)
Unrealized holding losses on available-for-sale securities										0.0	(0.1)
Reclassification for realized losses included in net (loss) income										0.0	(0.2)
Net change in unrealized (losses) gains on available-for-sale securities									0.0	0.0	(0.3)
Decrease in fair value of cash flow hedges									5.8	30.9	34.8
Reclassification for realized losses (gains) included in net loss									(40.4)	(41.5)	(100.6)
Net unrealized gains (losses) on cash flow hedges									(34.6)	(10.6)	(65.8)
Prior service credit (cost) for the period									0.0	0.0	0.0
Net actuarial gain (loss) for the period									0.0	7.5	7.1
Amortization of actuarial loss and prior service cost included in net (loss) income									(11.9)	(2.8)	(0.1)
Postretirement plans and workers' compensation obligations									(11.9)	4.7	7.0
Foreign currency translation adjustment									(34.9)	(41.0)	(92.7)
Other comprehensive loss from investment in subsidiaries									0.0	0.0	0.0
Other comprehensive income (loss), net of income taxes									(81.4)	(46.9)	(151.8)
Comprehensive loss									(1,217.2)	(606.0)	(757.4)
Less: Comprehensive income attributable to noncontrolling interests									7.1	9.7	12.3
Comprehensive loss attributable to common stockholders									(1,224.3)	(615.7)	(769.7)
Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									933.9	431.1	272.5
Unrealized holding losses on available-for-sale securities										0.0	0.0
Reclassification for realized losses included in net (loss) income										0.0	0.0
Net change in unrealized (losses) gains on available-for-sale securities									0.0	0.0	0.0
Decrease in fair value of cash flow hedges									0.0	0.0	0.0
Reclassification for realized losses (gains) included in net loss									0.0	0.0	0.0
Net unrealized gains (losses) on cash flow hedges									0.0	0.0	0.0
Prior service credit (cost) for the period									0.0	0.0	0.0
Net actuarial gain (loss) for the period									0.0	0.0	0.0
Amortization of actuarial loss and prior service cost included in net (loss) income									0.0	0.0	0.0
Postretirement plans and workers' compensation obligations									0.0	0.0	0.0
Foreign currency translation adjustment									0.0	0.0	0.0
Other comprehensive loss from investment in subsidiaries									21.8	150.2	(46.4)
Other comprehensive income (loss), net of income taxes									21.8	150.2	(46.4)
Comprehensive loss									955.7	581.3	226.1
Less: Comprehensive income attributable to noncontrolling interests									0.0	0.0	0.0
Comprehensive loss attributable to common stockholders									$ 955.7	$ 581.3	$ 226.1