Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Lease costs:
Operating lease costs	$ 2,865	$ 5,753
Variable operating lease costs	77	154
Total lease costs	2,942	5,907
Operating cash flows for operating leases	2,061	4,064	$ 0
Right-of-use assets obtained in exchange for lease obligations	$ 0	$ 51,597
Weighted-average remaining lease term (years) of operating leases	7 years	7 years
Weighted-average discount rate of operating leases	5.80%	5.80%