Supplemental Guarantor Information Supplemental Guarantor Information (Condensed Consolidating Statement of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Net cash used by operating activities				$ (372.1)	$ (235.3)
Cash flow from investing activities:
Capital expenditures				(40.5)	(41.7)
Payments for acquisitions		$ (5.8)		(5.9)	(5.6)	$ (5.6)
Proceeds from maturities of short-term investments				275.0	249.5
Payments for purchases of short-term investments				(126.5)	(260.7)
Proceeds from sale of assets				10.8	14.6
Increase in certain other assets				(22.8)	(26.9)
Capital contributions and loans paid				0.0	0.0
Proceeds from intercompany loans				0.0	0.0
Net cash used by investing activities				90.1	(70.8)
Cash flow from financing activities:
Dividends paid	$ 0.0		$ (7.6)	(7.7)	(22.9)
Debt issuance costs				38.9	1.1
Revolving credit facility (repayments) borrowings, net				185.0	120.0
Other debt borrowings				706.0	381.0
Other debt repayments				(306.7)	(433.5)
Distributions and payments to noncontrolling interest holders				(337.8)	(16.3)
Issuance of common shares				0.0	0.3
Repurchase of common shares				(3.0)	(4.8)
Capital contributions received and loans incurred				0.0	0.0
Payments on intercompany loans				0.0	0.0
Net cash provided by financing activities				196.9	22.7
Effect of exchange rate changes on cash and cash equivalents				(14.4)	19.3
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				(99.5)	(264.1)
Cash, cash equivalents and restricted cash at the beginning of the period	443.7		388.6	443.7	388.6	543.2	$ 652.7
Reportable Legal Entities [Member] | Parent Company [Member]
Net cash used by operating activities				(108.5)	(101.9)
Cash flow from investing activities:
Capital expenditures				(4.7)	(7.5)
Payments for acquisitions				0.0	0.0
Proceeds from maturities of short-term investments				74.0	0.4
Payments for purchases of short-term investments				0.0	(14.0)
Proceeds from sale of assets				6.7	0.0
Increase in certain other assets				(4.6)	(0.6)
Capital contributions and loans paid				(487.2)	(100.2)
Proceeds from intercompany loans				25.2	193.7
Net cash used by investing activities				(390.6)	71.8
Cash flow from financing activities:
Dividends paid				(7.7)	(22.9)
Debt issuance costs				38.9	1.1
Revolving credit facility (repayments) borrowings, net				115.0	0.0
Other debt borrowings				660.0	323.3
Other debt repayments				(274.5)	(344.3)
Distributions and payments to noncontrolling interest holders				0.0	0.0
Issuance of common shares					0.3
Repurchase of common shares				(3.0)	(4.8)
Capital contributions received and loans incurred				0.0	0.0
Payments on intercompany loans				0.0	0.0
Net cash provided by financing activities				450.9	(49.5)
Effect of exchange rate changes on cash and cash equivalents				0.0	0.0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				(48.2)	(79.6)
Cash, cash equivalents and restricted cash at the beginning of the period	10.3		59.3	10.3	59.3	58.5	138.9
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Net cash used by operating activities				(24.4)	(23.9)
Cash flow from investing activities:
Capital expenditures				(0.1)	(0.1)
Payments for acquisitions				0.0	0.0
Proceeds from maturities of short-term investments				0.0	0.0
Payments for purchases of short-term investments				0.0	0.0
Proceeds from sale of assets				0.0	0.0
Increase in certain other assets				0.0	3.9
Capital contributions and loans paid				0.0	0.0
Proceeds from intercompany loans				0.0	0.0
Net cash used by investing activities				(0.1)	3.8
Cash flow from financing activities:
Dividends paid				0.0	0.0
Debt issuance costs				0.0	0.0
Revolving credit facility (repayments) borrowings, net				0.0	0.0
Other debt borrowings				0.0	0.0
Other debt repayments				(0.3)	(1.1)
Distributions and payments to noncontrolling interest holders				0.0	0.0
Issuance of common shares					0.0
Repurchase of common shares				0.0	0.0
Capital contributions received and loans incurred				43.0	53.2
Payments on intercompany loans				(16.6)	(31.8)
Net cash provided by financing activities				26.1	20.3
Effect of exchange rate changes on cash and cash equivalents				0.0	0.0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				1.6	0.2
Cash, cash equivalents and restricted cash at the beginning of the period	3.9		2.5	3.9	2.5	2.3	2.3
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Net cash used by operating activities				(239.2)	(109.5)
Cash flow from investing activities:
Capital expenditures				(35.7)	(34.1)
Payments for acquisitions				(5.9)	(5.6)
Proceeds from maturities of short-term investments				201.0	249.1
Payments for purchases of short-term investments				(126.5)	(246.7)
Proceeds from sale of assets				4.1	14.6
Increase in certain other assets				(18.2)	(30.2)
Capital contributions and loans paid				0.0	0.0
Proceeds from intercompany loans				0.0	0.0
Net cash used by investing activities				18.8	(52.9)
Cash flow from financing activities:
Dividends paid				0.0	0.0
Debt issuance costs				0.0	0.0
Revolving credit facility (repayments) borrowings, net				70.0	120.0
Other debt borrowings				46.0	57.7
Other debt repayments				(31.9)	(88.1)
Distributions and payments to noncontrolling interest holders				(337.8)	(16.3)
Issuance of common shares					0.0
Repurchase of common shares				0.0	0.0
Capital contributions received and loans incurred				444.2	47.0
Payments on intercompany loans				(8.6)	(161.9)
Net cash provided by financing activities				181.9	(41.6)
Effect of exchange rate changes on cash and cash equivalents				(14.4)	19.3
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				(52.9)	(184.7)
Cash, cash equivalents and restricted cash at the beginning of the period	429.5		326.8	429.5	326.8	482.4	511.5
Consolidation, Eliminations [Member]
Net cash used by operating activities				0.0	0.0
Cash flow from investing activities:
Capital expenditures				0.0	0.0
Payments for acquisitions				0.0	0.0
Proceeds from maturities of short-term investments				0.0	0.0
Payments for purchases of short-term investments				0.0	0.0
Proceeds from sale of assets				0.0	0.0
Increase in certain other assets				0.0	0.0
Capital contributions and loans paid				487.2	100.2
Proceeds from intercompany loans				(25.2)	(193.7)
Net cash used by investing activities				462.0	(93.5)
Cash flow from financing activities:
Dividends paid				0.0	0.0
Debt issuance costs				0.0	0.0
Revolving credit facility (repayments) borrowings, net				0.0	0.0
Other debt borrowings				0.0	0.0
Other debt repayments				0.0	0.0
Distributions and payments to noncontrolling interest holders				0.0	0.0
Issuance of common shares					0.0
Repurchase of common shares				0.0	0.0
Capital contributions received and loans incurred				(487.2)	(100.2)
Payments on intercompany loans				25.2	193.7
Net cash provided by financing activities				(462.0)	93.5
Effect of exchange rate changes on cash and cash equivalents				0.0	0.0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				0.0	0.0
Cash, cash equivalents and restricted cash at the beginning of the period	$ 0.0		$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 0.0