Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 10,001,209	$ 17,115,988
Adjustments to reconcile net income to net cash provided in operating activities:
Depreciation and amortization	70,037	256,610
Stock-based compensation expense	1,173,714	520,387
Deferred tax expense (benefit)	(265,203)	199,908
Non-cash lease expense	57,708
(Accretion) amortization of bond (discount) premium	790,006	(53,735)
Changes in operating assets and liabilities:
Accounts receivable	5,472,278	(1,250,070)
Income tax payable	(354,984)	(949,791)
Prepaid expenses and other current assets	(915,142)	(189,959)
Patent costs		(189,704)
Accounts payable, accrued expenses and lease obligation	413,127	(921,360)
Net cash provided by operating activities	16,442,750	14,538,274
Cash flows from investing activities:
Purchases of property and equipment	(69,470)
Maturities of marketable securities	87,283,693	76,636,059
Purchases of marketable securities	(105,431,394)	(93,357,599)
Net cash used in investing activities	(18,217,171)	(16,721,540)
Cash flows from financing activities:
Proceeds from stock option exercises	61,725	2,133,396
Payments for repurchases of common stock	(412,761)	(357,289)
Net cash (used in) provided by financing activities	(351,036)	1,776,107
Decrease in cash and cash equivalents	(2,125,457)	(407,159)
Cash and cash equivalents at beginning of year	4,999,183	13,176,452
Cash and cash equivalents at end of period	2,873,726	12,769,293
Cash paid during the year for:
Taxes	$ 3,473,278	$ 4,462,362