Stock Plans - Summary of Treasury Share Transactions Under the Company's Stock Repurchase Program (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Equity [Abstract]
Common shares at the beginning of period, Number of Shares	4,838	4,714	4,833	4,714
Common shares purchased, Number of Shares	25	0	30	0
Common shares at the end of period, Number of Shares	4,863	4,714	4,863	4,714
Common shares at the beginning of period, Amount	$ (71,466)	$ (70,459)	$ (71,438)	$ (70,459)
Common shares purchased, Amount	(201)	0	(229)	0
Common shares at the end of period, Amount	$ (71,667)	$ (70,459)	$ (71,667)	$ (70,459)