v3.8.0.1

Debt and Credit Facility Components (Details) - USD ($) $ in Millions	Sep. 30, 2017	Mar. 31, 2017	Feb. 28, 2017	Feb. 28, 2015
Debt Instrument [Line Items]
Amount of unamortized debt discount of debentures	$ (1,437.7)	$ (1,516.5)
Debt issuance costs	(43.0)	(46.8)	$ (33.7)
December 2015 Amended Credit Facility with Maturity Dates of June 2018 and February 2020
Debt Instrument [Line Items]
Debt issuance costs	(7.0)	(8.5)
2017 Senior Subordinated Convertible Debt
Debt Instrument [Line Items]
Amount of unamortized debt discount of debentures	(642.2)	(667.5)
Debt issuance costs	(16.9)	(17.6)
2015 Senior Subordinated Convertible Debt
Debt Instrument [Line Items]
Amount of unamortized debt discount of debentures	(423.8)	(446.6)
Debt issuance costs	(15.7)	(16.6)
2017 Junior Subordinated Convertible Debt
Debt Instrument [Line Items]
Amount of unamortized debt discount of debentures	(360.5)	(309.3)
Debt issuance costs	(3.3)	(3.4)		$ (30.3)
2007 Junior Subordinated Convertible Debt
Debt Instrument [Line Items]
Amount of unamortized debt discount of debentures	(11.2)	(93.1)
Debt issuance costs	$ (0.1)	$ (0.7)

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- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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