Gulf Island Fabrication, Inc. Annual report pursuant to Section 13 and 15(d)

Revenue, Contract Assets and Liabilities and Other Contract Matters - Schedules of Concentration of Risk, by Risk Factor (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 57,561	$ 54,869	$ 59,974	$ 78,555	$ 79,445	$ 75,802	$ 80,456	$ 67,605	$ 250,959	$ 303,308	$ 221,247
Sales Revenue, Net \| Customer Concentration Risk \| Customer A
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue									37,986	52,310
Sales Revenue, Net \| Customer Concentration Risk \| Customer B
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue									$ 77,342	39,897
Sales Revenue, Net \| Customer Concentration Risk \| Customer C
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue										36,175	49,123
Sales Revenue, Net \| Customer Concentration Risk \| Customer D
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue										$ 34,448
Sales Revenue, Net \| Customer Concentration Risk \| Customer E
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue											25,873
Sales Revenue, Net \| Customer Concentration Risk \| Customer F
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue											$ 23,279