Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 47,377,000	$ 46,703,000	$ 35,695,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	22,516,000	22,984,000	21,775,000
Loss on write down or disposal of property, capitalized software or investment	149,000	306,000	1,199,000
Stock compensation expense	4,485,000	4,349,000	3,164,000
Provision for doubtful accounts	1,606,000	1,875,000	2,559,000
Deferred income taxes	1,470,000	1,456,000	(874,000)
Changes in operating assets and liabilities:
Accounts receivable	3,964,000	(8,271,000)	(4,658,000)
Customer deposits	(3,723,000)	(9,772,000)	(3,025,000)
Prepaid expenses and income taxes	(3,834,000)	(66,000)	(2,166,000)
Other assets	(595,000)	145,000	545,000
Accounts and income taxes payable	1,095,000	(1,975,000)	(3,130,000)
Accrued liabilities	11,885,000	20,905,000	11,068,000
Operating lease liabilities	(5,569,000)	0	0
Net cash provided by operating activities	80,826,000	78,639,000	62,152,000
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(32,360,000)	(15,274,000)	(27,689,000)
Net cash used in investing activities	(32,360,000)	(15,274,000)	(27,689,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Exercise of employee stock purchase options	505,000	503,000	458,000
Exercise of common stock options	8,147,000	7,241,000	3,426,000
Purchase of treasury stock	(65,608,000)	(35,167,000)	(11,187,000)
Net cash used in financing activities	(56,956,000)	(27,423,000)	(7,303,000)
Net (decrease) increase in cash and cash equivalents	(8,490,000)	35,942,000	27,160,000
Cash and cash equivalents at beginning of year	91,713,000	55,771,000	28,611,000
CASH AND CASH EQUIVALENTS AT END OF YEAR	83,223,000	91,713,000	55,771,000
Supplemental cash flow information
Income taxes paid	15,077,000	12,854,000	16,229,000
Accrual of software license purchase	$ 3,790,000	$ 0	$ 1,746,000