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		Dec. 31, 2017	Mar. 31, 2017
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%
Convertible Senior Subordinated 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		1.25%
Convertible Senior Subordinated Notes | April 2013 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		1.25%
Carrying Value
Assets:
Investment in Pop's mandatorily redeemable preferred stock units		$ 96.4	$ 96.8
Liabilities:
Total liabilities, fair value disclosure		2,692.1	3,428.1
Carrying Value | Term Loan | Term Loan A Facility
Liabilities:
Loans, fair value disclosure		928.1	961.8
Carrying Value | Term Loan | Term Loan B-1 Facility
Liabilities:
Loans, fair value disclosure	[1]	806.1
Carrying Value | Term Loan | Term Loan B Facility
Liabilities:
Loans, fair value disclosure	[1]		1,554.7
Carrying Value | Senior Notes | 5.875% Senior Notes
Liabilities:
Senior Notes, fair value disclosure		500.0	498.3
Carrying Value | Convertible Senior Subordinated Notes | April 2013 Notes
Liabilities:
Convertible notes, fair value disclosures		60.0	60.0
Carrying Value | Production Loans | Production Loans
Liabilities:
Loans, fair value disclosure		397.9	353.3
Fair Value | Fair Value (Level 3)
Assets:
Investment in Pop's mandatorily redeemable preferred stock units		122.1	122.1
Fair Value | Fair Value (Level 2)
Liabilities:
Total liabilities, fair value disclosure		2,791.0	3,548.2
Fair Value | Fair Value (Level 2) | Term Loan | Term Loan A Facility
Liabilities:
Loans, fair value disclosure		957.7	983.8
Fair Value | Fair Value (Level 2) | Term Loan | Term Loan B-1 Facility
Liabilities:
Loans, fair value disclosure	[1]	826.0
Fair Value | Fair Value (Level 2) | Term Loan | Term Loan B Facility
Liabilities:
Loans, fair value disclosure	[1]		1,610.0
Fair Value | Fair Value (Level 2) | Senior Notes | 5.875% Senior Notes
Liabilities:
Senior Notes, fair value disclosure		549.3	542.1
Fair Value | Fair Value (Level 2) | Convertible Senior Subordinated Notes | April 2013 Notes
Liabilities:
Convertible notes, fair value disclosures		59.6	58.5
Fair Value | Fair Value (Level 2) | Production Loans | Production Loans
Liabilities:
Loans, fair value disclosure		$ 398.4	$ 353.8

[1] As of March 31, 2017, amounts were outstanding under the previous Term Loan B facility (see Note 6).