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

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Debt - Partial Redemption of 4.125% Senior Secured Notes - Additional Information (Detail) € in Thousands, $ in Millions				3 Months Ended	6 Months Ended		12 Months Ended
	Oct. 12, 2018 USD ($)	Oct. 12, 2018 EUR (€)	Oct. 09, 2018 EUR (€)	Mar. 31, 2018 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2018
Debt Instrument [Line Items]
Loss on extinguishment of debt \| $				$ 23	$ 3	$ 24
4.125% Senior Secured Notes due 2024 \| Acquisition Corp.
Debt Instrument [Line Items]
Due date of senior secured notes	2024	2024			2024		2024
Redemptions of senior notes		€ 34,500	€ 34,500
Interest rate		4.125%	4.125%		4.125%		4.125%
Senior notes redemption price		€ 36,170
Redemption price, percentage of principal amount redeemed	103.00%	103.00%
Debt instrument remaining outstanding amount		€ 310,500
Loss on extinguishment of debt \| $	$ 2
3.625% Senior Secured Notes due 2026
Debt Instrument [Line Items]
Interest rate					3.625%
3.625% Senior Secured Notes due 2026 \| Acquisition Corp.
Debt Instrument [Line Items]
Due date of senior secured notes			2026		2026
Interest rate		3.625%	3.625%		3.625%