Stockholders' Deficit - Stock Repurchase Program (Details) - USD ($)	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 06, 2018	Apr. 18, 2018	Jun. 08, 2017	Apr. 26, 2016	Jan. 22, 2015
Class of Stock [Line Items]
Approved stock repurchase program, authorized amount (up to)				$ 100,000,000	$ 200,000,000	$ 200,000,000.0	$ 400,000,000.0	$ 450,000,000.0
Repurchase of common stock, amount	$ 100,000,000	$ 50,000,000
Remaining capacity under the stock repurchase program	$ 296,300,000		$ 296,300,000
Open Market Transaction
Class of Stock [Line Items]
Repurchase of common stock (in shares)	1,175,531		1,648,907
Repurchase of common stock, amount	$ 100,000,000		$ 150,000,000