Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Trade accounts receivable, allowances for doubtful accounts	$ 1,231	$ 1,223
Intangible assets, accumulated amortization	$ 34,411	$ 33,672
Partners’ capital:
Common units issued (in shares)	141,213,944	140,386,811
Common units outstanding (in shares)	141,213,944	140,386,811