Business Realignment Expenses - Narrative (Details) $ in Thousands		3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 25, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 16, 2017 ft²
Restructuring Cost and Reserve [Line Items]
Impairment of intangible assets			$ 0	$ 1,028
Restructuring charges			2,082
Restructuring reserve		$ 3,180	1,739		$ 3,180
Other Operating Expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges			2,100
Bethesda, Maryland | Office Building
Restructuring Cost and Reserve [Line Items]
Area of real estate property | ft²						18,412
District of Columbia | Other Operating Expense | Office Building
Restructuring Cost and Reserve [Line Items]
Loss on contract termination					2,000
Payment on contract loss termination			800
Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1,372
Restructuring reserve		1,192	70		1,192
Employee Severance | Corporate and Other
Restructuring Cost and Reserve [Line Items]
Restructuring costs			500
Restructuring charges			462
Restructuring reserve		399	11		399
General and Administrative Expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges			900
Selling and Marketing Expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges			200
Technology and Operations
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1,000
CAG
Restructuring Cost and Reserve [Line Items]
Restructuring costs			1,500
CAG | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring costs		900	1,000
Restructuring charges			910
Restructuring reserve		793	59		793
CAG | Employee Severance | Severance Agreement
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 300
CAG | Legal and Administrative Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs		$ 100
IronDirect
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges					900
Reversal of earn-out liability					900
IronDirect | Leasehold Improvements
Restructuring Cost and Reserve [Line Items]
Impairment of long-lived assets					600
IronDirect | Contract-Based Intangible Assets
Restructuring Cost and Reserve [Line Items]
Impairment of intangible assets					1,200
IronDirect | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring costs					$ 100
IronDirect | Occupancy And Contract Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs			$ 100