Note 3 - Investments - Realized Gains and Losses Related to the Sale of Securities (Details) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Gross gains	$ 3,951	$ 530	$ 3,951	$ 530
Gross losses	(18,479)	(857)	(18,479)	(857)
Net security gains (losses)	$ (14,528)	$ (327)	$ (14,528)	$ (327)

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