Employee Deferred Savings Plan - Company Recorded Contributions To Plan (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Deferred savings plan contributions	$ 1.7	$ 1.6	$ 3.7	$ 3.5

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration