Debt and Credit Facility - Senior Secured Notes (Details) - USD ($)	3 Months Ended
Jun. 30, 2019	Mar. 31, 2019	May 31, 2018
Debt Instrument [Line Items]
Debt issuance costs, net	$ 77,600,000	$ 83,600,000	$ 24,400,000
Debt instrument, unamortized discount	$ 1,238,900,000	1,268,700,000	10,500,000
2021 Senior Secured Notes
Debt Instrument [Line Items]
Debt instrument, face amount			$ 1,000,000,000.00
Debt instrument, interest rate, stated percentage	3.922%		3.922%
Debt issuance costs, net	$ 7,800,000	8,800,000
Debt instrument, unamortized discount	$ 3,400,000	3,800,000
Effective Interest Rate			3.922%
Debt instrument, redemption price, percentage	100.00%
Senior Secured Notes, 2023
Debt Instrument [Line Items]
Debt instrument, face amount			$ 1,000,000,000.00
Debt instrument, interest rate, stated percentage	4.333%		4.333%
Debt issuance costs, net	$ 9,600,000	10,200,000
Debt instrument, unamortized discount	$ 4,200,000	$ 4,400,000
Effective Interest Rate			4.333%
Senior Secured Notes, 2023 \| Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	100.00%
Senior Secured Notes, 2023 \| Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	100.00%
Senior Secured Notes
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	101.00%

Face (par) amount of debt instrument at time of issuance.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

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

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

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Amount, after accumulated amortization, of debt discount.

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

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