Benefit Plans (Narrative) (Details)		3 Months Ended	12 Months Ended
	Oct. 15, 2018	Mar. 31, 2023 USD ($) installment quarter shares	Mar. 31, 2023 USD ($) installment plan quarter $ / shares shares	Mar. 31, 2022 USD ($) $ / shares shares	Mar. 31, 2021 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum contribution from employer			50.00%
Employer matching contribution, percent			6.00%
Employer contribution, percent of match			3.00%
Amount of cost recognized			$ 1,700,000	$ 1,800,000	$ 1,600,000
Number of executive retirement plans | plan			2
Annual salary increase used for estimating unfunded liability		3.50%
Discount rate used for estimating unfunded liability		6.00%	6.00%
Retirement age used for estimating unfunded liability		65
Stock Option Plans
Number of shares available for grant (in shares) | shares		145,031	145,031
Percentage of shares subject to performance shares			100.00%
Weighted-average fair value at the grant date | $ / shares			$ 53.57	$ 99.14	$ 58.48
Schedule of vesting of restricted shares on basis of compounded annual EPS growth [Abstract]
Stock-based compensation			$ 9,052,835	$ 17,582,995	$ 19,281,278
Stock Options Plans
Stock Option Plans
Shares of authorized common stock reserved for issuance (in shares) | shares		3,350,000	3,350,000
Compensation Cost Not yet Recognized
Total unrecognized stock-based compensation expense related to non-vested stock options		$ 3,100,000	$ 3,100,000
Weighted average period for recognition			1 year 9 months 18 days
Schedule of vesting of restricted shares on basis of compounded annual EPS growth [Abstract]
Weighted average period for recognition			1 year 9 months 18 days
Stock-based compensation			$ 2,442,309	$ 3,473,913	$ 3,804,674
Outstanding number | shares		314,742	314,742	348,743
Options exercisable, end of period (in shares) | shares		114,757	114,757
Stock Options Plans | Scenario 1
Schedule of vesting of restricted shares on basis of compounded annual EPS growth [Abstract]
Outstanding number | shares		86,811	86,811
Stock Options Plans | Scenario 2
Schedule of vesting of restricted shares on basis of compounded annual EPS growth [Abstract]
Outstanding number | shares		113,174	113,174
Restricted Stock
Stock Option Plans
Number of installments | installment		6	6
Compensation Cost Not yet Recognized
Weighted average period for recognition			1 year 3 months 18 days
Restricted Stock
Granted during the period (in shares) | shares			3,250	4,062	52,735
Granted during the period (in dollars per share) | $ / shares			$ 129.85	$ 188.38	$ 106.28
Schedule of vesting of restricted shares on basis of compounded annual EPS growth [Abstract]
Weighted average period for recognition			1 year 3 months 18 days
Stock-based compensation			$ 6,610,526	$ 14,109,082	$ 15,476,604
Unrecognized compensation cost related to unvested restricted stock		$ 4,400,000	$ 4,400,000
Performance Shares
Stock Option Plans
Vesting period	10 years
Number of consecutive quarters | quarter		4	4
Service Options
Stock Option Plans
Vesting period			10 years
Number of installments | installment		6	6
Minimum | Stock Options Plans
Stock Option Plans
Vesting period			3 years
Maximum | Stock Options Plans
Stock Option Plans
Expiration period			10 years
Vesting period			6 years
Supplemental Employee Retirement Plans, Defined Benefit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pension and other postretirement benefits cost (reversal of cost)			$ 500,000	500,000	$ 600,000
Unfunded liability		$ 5,700,000	$ 5,700,000	$ 5,900,000