Note 2 - Investments - Realized Gains and Losses Related to the Sale of Securities (Details) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Gross gains	$ 2,400	$ 54,266	$ 218,411	$ 119,173
Gross losses	0	(1,739)	(398)	(291,524)
Net realized gains (losses)	2,400	52,527	218,013	(172,351)
Gross gains	2,400	54,266	218,411	119,173
Gross losses	$ 0	$ (1,739)	$ (398)	$ (291,524)

The gross gain realized from the sale, exchange, redemption, or retirement of securities, not separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

No definition available.

Name:	usac_GainOnSaleOfSecuritiesGross
Namespace Prefix:	usac_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration