Consolidated Balance Sheets (Parenthetical) - USD ($)	Mar. 31, 2021	Mar. 31, 2020
Statement Of Financial Position [Abstract]
Allowance for doubtful debts, accounts receivable	$ 3,274,000	$ 5,133,000
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	54,529,642	54,254,557
Common stock, shares outstanding	17,876,090	17,968,966
Treasury stock, shares	36,653,552	36,285,591