Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
Dec. 31, 2018	Dec. 31, 2019	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested, compensation not yet recognized, stock options		$ 40,600
Nonvested, compensation not yet recognized, period		3 years
Arrangement by share-based payment award (in USD per share)	$ 12.90	$ 8.81	$ 8.76	$ 2.21
Granted (in USD per share)	$ 0.00	$ 9.50	$ 7.29	$ 0.00
Total State	$ 0	$ 0	$ 2	$ 1
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Granted (in USD per share)	$ 22.54	$ 15.46
Fair value of shares vested	$ 1,300	$ 8,900	300	1,400
Intrinsic value of stock-options exercised	$ 13,300	$ 14,700	$ 7,800	$ 2,600
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested, compensation not yet recognized, period	1 year 2 months 4 days	4 months 24 days
Unrecognized compensation costs	$ 300	$ 300
RSUs forfeited in period (in shares)	1,500	0
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested, compensation not yet recognized, period	3 years 18 days	9 months 18 days
Granted (in USD per share)	$ 0	$ 17.18
Fair value of shares vested		$ 1,100
Unrecognized compensation costs	$ 3,000	$ 4,900

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Weighted average grant-date fair value of non-vested options outstanding.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Amount of state and local current and deferred income tax expense (benefit) attributable to continuing operations.

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