Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2021	Mar. 31, 2020
Significant Accounting Policies [Line Items]
Equity compensation expense	$ 23,745	$ 14,331	$ 49,911	$ 23,914
Unrecognized compensation expense	233,469		233,469
Allowance for credit losses	$ 22,833	$ 28,028	$ 22,833	$ 28,028	$ 24,126	$ 22,360