Fair Value Measurements (Carrying Values And Fair Values Of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Mar. 31, 2020
Senior Notes \| 5.875% Senior Notes
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Coupon rate	5.875%
Senior Notes \| 6.375% Senior Notes
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Coupon rate	6.375%
Carrying Value
Liabilities:
Financing component of interest rate swaps, fair value disclosure	$ 161.5	$ 0.0
Carrying Value \| Term Loan \| Term Loan A
Liabilities:
Loans, fair value disclosure	675.6	699.8
Carrying Value \| Term Loan \| Term Loan B
Liabilities:
Loans, fair value disclosure	947.8	952.9
Carrying Value \| Senior Notes \| 5.875% Senior Notes
Liabilities:
Senior Notes, fair value disclosure	505.4	504.0
Carrying Value \| Senior Notes \| 6.375% Senior Notes
Liabilities:
Senior Notes, fair value disclosure	540.0	539.2
Carrying Value \| Production Loans \| Production Loans
Liabilities:
Loans, fair value disclosure	155.2	151.3
Fair Value \| Fair Value (Level 2)
Liabilities:
Financing component of interest rate swaps, fair value disclosure	161.3	0.0
Fair Value \| Fair Value (Level 2) \| Term Loan \| Term Loan A
Liabilities:
Loans, fair value disclosure	651.9	637.7
Fair Value \| Fair Value (Level 2) \| Term Loan \| Term Loan B
Liabilities:
Loans, fair value disclosure	934.9	845.7
Fair Value \| Fair Value (Level 2) \| Senior Notes \| 5.875% Senior Notes
Liabilities:
Senior Notes, fair value disclosure	496.7	430.5
Fair Value \| Fair Value (Level 2) \| Senior Notes \| 6.375% Senior Notes
Liabilities:
Senior Notes, fair value disclosure	538.8	452.9
Fair Value \| Fair Value (Level 2) \| Production Loans \| Production Loans
Liabilities:
Loans, fair value disclosure	$ 155.2	$ 151.3

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13433-108611

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Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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