Tax Receivable Agreement Liability (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2018	Sep. 30, 2017	Mar. 31, 2018	Mar. 31, 2017	Jun. 30, 2017
Tax Receivable Agreement [Line Items]
Tax receivable agreement, percentage of realized cash saving in tax to pass through	8500.00%		8500.00%
Tax Receivable Agreement [Roll Forward]
Payable pursuant to tax receivable agreement		$ 82,291,000	$ 82,291,000	$ 93,750,000	$ 93,750,000
Additions (reductions) to tax receivable agreement:
Adjustment to tax receivable agreement liability	$ 30,317,000	2,615,000	(27,702,000)	$ 0	8,140
Payments under tax receivable agreement			0		(4,279,000)
Payable pursuant to tax receivable agreement	56,073,000		56,073,000		82,291,000
Less current portion under tax receivable agreement	(4,323,000)		(4,323,000)		(4,332,000)
Payable pursuant to tax receivable agreement		$ 77,959,000	77,959,000
Deferred Tax Assets, Investment in Subsidiaries	$ 106,107,000		106,107,000		109,375,000
Exchange of LLC Units for Class A Shares
Additions (reductions) to tax receivable agreement:
Exchange of LLC Units for Class A Common Stock			1,484,000		960,000
Adjustment to tax receivable agreement liability			$ (27,702,000)		$ (8,140,000)