Stockholders' Equity - Per Share Results (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019
Earnings per share:
Net (loss) income	$ 1,981	$ (255)	$ (768)	$ (286)
Weighted average shares outstanding for computation of basic per share results	5,663,000	5,075,000	6,236,000	5,088,000
Incremental shares from assumed exercise of Griffin stock options	181,000
Adjusted weighted average shares for computation of diluted per share results	5,844,000	5,075,000	6,236,000	5,088,000
Incremental shares from assumed exercise of stock options excluded due to anti-dilutive effect			95,000	52,000	51,000
Warrant
Earnings per share:
Incremental shares from assumed exercise of stock options excluded due to anti-dilutive effect			515,747