Fair Value Measurements - Contingent Consideration Liability (Details) $ in Thousands		3 Months Ended			6 Months Ended
	May 26, 2017 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($) item	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) item	Jun. 30, 2017 USD ($)	May 31, 2017 USD ($)
Additional information
Number of unobservable inputs | item			2		2
Minimum probability of acquired entity meeting contractual operating performance target (as a percent)					33.00%
Maximum probability of acquired entity meeting contractual operating performance target (as a percent)					100.00%
Contingent consideration credited to non-operating income			$ (771)	$ (13)	$ (783)	$ (13)
FGC
Additional information
Potential contingent consideration	$ 1,500						$ 1,500
Fair value of the contingent consideration	1,200						$ 1,200
Cash payment made	$ 33,000
FGC | Forecast
Additional information
Cash payment made		$ 1,500
Contingent Consideration Liability | Significant Unobservable Inputs (Level 3)
Rollforward of contingent consideration liability level three fair value measurements
Beginning balance		$ 1,500			716
Change in fair value of contingent consideration liability during year					784	13
Ending balance			$ 1,500	$ 1,213	$ 1,500	1,213
Contingent Consideration Liability | Significant Unobservable Inputs (Level 3) | FGC
Rollforward of contingent consideration liability level three fair value measurements
FGC acquisition						$ 1,200