Fair Value Measurements (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Assets:
Cash and cash equivalents	$ 118,639	$ 36,584
Short-term investments	6,042	13,170
Restricted cash		25,141
Other assets	6,825	6,817
Liabilities:
Deferred compensation	6,249	5,644
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	118,639	36,584
Short-term investments	6,042	13,170
Restricted cash		25,141
Other assets	0	0
Liabilities:
Deferred compensation	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Short-term investments	0	0
Restricted cash		0
Other assets	6,825	6,817
Liabilities:
Deferred compensation	6,249	5,644
Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Short-term investments	0	0
Restricted cash		0
Other assets	0	0
Liabilities:
Deferred compensation	$ 0	$ 0