Note 2 - Investments - Realized Gains and Losses Related to the Sale of Securities (Details) - USD ($)	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Gross gains	$ 52,792	$ 44,295
Gross losses	(395)	(263,248)
Realized gains (losses)	$ 52,397	$ (218,953)

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