RESTATEMENT OF PREVIOUSLY ISSUED CONSOLIDATED FINANCIAL STATEMENTS, Consolidated Balance Sheets (Parenthetical) (Details) - USD ($)	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	[1]	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]
ASSETS [Abstract]
Allowance for doubtful accounts	$ 15,940	$ 12,940	$ 15,703		$ 9,839	$ 9,911	$ 16,075	$ 22,642
Accumulated amortization	$ 547,369	$ 714,000	$ 690,869		$ 712,000	$ 712,000	$ 711,000	$ 688,147
STOCKHOLDERS' EQUITY: [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10	$ 0.10		$ 0.10	$ 0.10	$ 0.10	$ 0.10
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000	20,000,000		20,000,000	20,000,000	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0	0		0	0	0	0
Preferred stock, shares outstanding (in shares)	0	0	0		0	0	0	0
Common stock, par value (in dollars per share)	$ 0.0024	$ 0.0024	$ 0.0024		$ 0.0024	$ 0.0024	$ 0.0024	$ 0.0024
Common stock, shares authorized (in shares)	25,000,000	25,000,000	25,000,000		25,000,000	25,000,000	25,000,000	25,000,000
Common stock, shares issued (in shares)	10,446,563	10,354,563	10,353,155		10,336,717	10,336,717	10,336,717	10,320,069
Treasury stock, shares (in shares)	1,424,376	1,420,539	1,292,594		1,182,509	1,182,502	1,121,607	1,049,207
Accumulated other comprehensive loss, tax	$ 358,646		$ 480,112				$ 240,045	$ 240,045

[1] As described in Note 2 to these Consolidated Financial Statements, we have restated the Consolidated Financial Statements.