Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Weighted Average Exercise Price [Roll Forward]
Granted (in USD per share)	$ 0.00	$ 9.50		$ 7.29	$ 0.00
Employee Stock Option
Share Equivalent
Options outstanding, start of year (in shares)	3,549,000	4,757,000
Granted (in shares)	2,002,000	3,614,000
Exercise of stock options (in shares)	(706,000)	(1,207,000)
Expired or forfeited (in shares)	(88,000)	(1,263,000)
Options outstanding, end of year (in shares)	4,757,000	5,901,000	4,757,000	3,549,000
Vested, end of year (in shares)	1,504,000	1,150,000	1,504,000
Weighted Average Exercise Price [Roll Forward]
Weighted average exercise price, options outstanding, start of year (in USD per share)	$ 7.58	$ 14.30
Granted (in USD per share)	22.54	15.46
Exercised (in USD per share)	3.71	3.17
Expired or forfeited (in USD per share)	15.57	17.78
Weighted average exercise price, options outstanding, end of year (in USD per share)	14.30	16.54	$ 14.30	$ 7.58
Vested, end of year (in USD per share)	$ 4.23	$ 14.72	$ 4.23
Weighted average remaining contractual term (years) [Roll Forward]
Weighted average remaining contractual term	5 years 5 months 1 day	5 years 10 months 24 days	5 years 5 months 1 day	4 years 5 months 4 days
Weighted average remaining contractual term, end of year	3 years 4 months 28 days	4 years 7 months 9 days
Intrinsic value [Roll Forward]
Options, outstanding, intrinsic value	$ 18,618	$ 30,145	$ 18,618	$ 57,123
Options, vested, outstanding, intrinsic value end of year	$ 15,098	$ 8,276	$ 15,098
Performance Shares
Share Equivalent
Options outstanding, start of year (in shares)	538,000	538,000
Granted (in shares)	0	800,000			0	0
Exercise of stock options (in shares)	0	0
Expired or forfeited (in shares)	0	(501,000)
Options outstanding, end of year (in shares)	538,000	837,000	538,000	538,000
Vested, end of year (in shares)	38,000	50,000	38,000
Weighted Average Exercise Price [Roll Forward]
Weighted average exercise price, options outstanding, start of year (in USD per share)	$ 13.09	$ 13.09
Granted (in USD per share)	0	17.18
Exercised (in USD per share)	0	0
Expired or forfeited (in USD per share)	0	13.05
Weighted average exercise price, options outstanding, end of year (in USD per share)	13.09	17.03	$ 13.09	$ 13.09
Vested, end of year (in USD per share)	$ 11.86	$ 18.74	$ 11.86
Weighted average remaining contractual term (years) [Roll Forward]
Weighted average remaining contractual term	6 years 14 days	6 years 3 months 3 days	6 years 14 days	6 years 6 months 14 days
Weighted average remaining contractual term, end of year	5 years 11 months 8 days	6 years 10 months 17 days
Intrinsic value [Roll Forward]
Options, outstanding, intrinsic value	$ 772	$ 3,456	$ 772	$ 5,688
Options, vested, outstanding, intrinsic value end of year	$ 91	$ 121	$ 91