Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 35,695,000	$ 29,479,000	$ 28,525,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	21,775,000	20,948,000	19,952,000
Loss on write down or disposal of assets	1,199,000	733,000	286,000
Stock-based compensation expense	3,164,000	2,432,000	2,192,000
Provision for doubtful accounts	2,559,000	2,335,000	1,357,000
Provision for deferred income taxes	(874,000)	(1,220,000)	(1,656,000)
Changes in operating assets and liabilities:
Accounts receivable	(4,658,000)	(5,429,000)	(3,567,000)
Customer deposits	(3,025,000)	(6,822,000)	(8,331,000)
Prepaid expenses and income taxes	(2,166,000)	(11,000)	6,742,000
Other assets	545,000	(29,000)	(516,000)
Accounts and taxes payable	(3,130,000)	3,350,000	(2,537,000)
Accrued liabilities	11,068,000	6,286,000	8,864,000
Net cash provided by operating activities	62,152,000	52,052,000	51,311,000
CASH FLOWS FROM INVESTING ACTIVITIES
Investment in private equity	0	34,000	(600,000)
Purchases of property and equipment	(27,689,000)	(31,041,000)	(16,756,000)
Net cash used in investing activities	(27,689,000)	(31,007,000)	(17,356,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Exercise of employee stock purchase options	458,000	419,000	371,000
Exercise of common stock options	3,426,000	2,367,000	3,749,000
Tax benefits from stock options	0	0	713,000
Purchase of treasury stock	(11,187,000)	(27,999,000)	(31,525,000)
Net cash used in financing activities	(7,303,000)	(25,213,000)	(26,692,000)
Net increase (decrease) in cash and cash equivalents	27,160,000	(4,168,000)	7,263,000
Cash and cash equivalents at beginning of year	28,611,000	32,779,000	25,516,000
CASH AND CASH EQUIVALENTS AT END OF YEAR	55,771,000	28,611,000	32,779,000
Supplemental cash flow information
Income taxes paid	16,229,000	18,321,000	13,589,000
Accrual of software license purchase	1,746,000	3,492,000	3,249,000
Tenant improvement allowance	$ 0	$ 1,224,000	$ 0