Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net income	$ 508,000	$ 550,000
Other comprehensive income (loss):
Change in unrealized gain (loss) on marketable securities, net of tax		(77,000)
Comprehensive income	$ 508,000	$ 473,000