STOCK BASED COMPENSATION (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restricted Stock Awards [Member]
Weighted Average Grant Date Fair Value
Costs are expected to be recognized over a weighted average period	1 year 6 months 22 days	1 year 2 months 12 days
LMI Aerospace, Inc. 2005 Long-Term Incentive Plan [Member]
Weighted Average Grant Date Fair Value
Compensation expense	$ 1,284	$ 1,850	$ 1,615
LMI Aerospace, Inc. 2005 Long-Term Incentive Plan [Member] | Restricted Stock Awards [Member]
Shares
Outstanding beginning balance (in shares)	296,782
Granted (in shares)	131,703
Vested (in shares)	(131,986)
Forfeited (in shares)	(43,065)
Outstanding ending balance (in shares)	253,434	296,782
Weighted Average Grant Date Fair Value
Outstanding beginning balance (in dollars per share)	$ 16.58
Granted (in dollars per share)	13.22
Vested (in dollars per share)	17.57
Forfeited (in dollars per share)	15.31
Outstanding ending balance (in dollars per share)	$ 14.54	$ 16.58
Unrecognized compensation costs	$ 1,762	$ 2,036
Fair value of restricted stock awards that vested	1,559	$ 1,083	$ 602
LMI Aerospace, Inc. 2015 Long-term Incentive Plan [Member]
Weighted Average Grant Date Fair Value
Compensation expense	$ 303
LMI Aerospace, Inc. 2015 Long-term Incentive Plan [Member] | Restricted Stock Awards [Member]
Shares
Outstanding beginning balance (in shares)	0
Granted (in shares)	61,801
Vested (in shares)	0
Forfeited (in shares)	0
Outstanding ending balance (in shares)	61,801	0
Weighted Average Grant Date Fair Value
Outstanding beginning balance (in dollars per share)	$ 0.00
Granted (in dollars per share)	9.79
Vested (in dollars per share)	0.00
Forfeited (in dollars per share)	0.00
Outstanding ending balance (in dollars per share)	$ 9.79	$ 0.00
Unrecognized compensation costs	$ 303
Costs are expected to be recognized over a weighted average period	6 months 4 days