Loss Per Share - Average Market Price of Common Stock and the Incremental Shares that were Dilutive or Potentially Dilutive (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded From Computation Of Earnings Per Share
Average market price of Real Industry common stock	$ 2.69	$ 7.02	$ 9.22
Potentially dilutive common stock equivalents:
Total potentially dilutive common stock equivalents	2,658,579	3,147,787	2,763,306
Restricted Common Stock Awards
Potentially dilutive common stock equivalents:
Total potentially dilutive common stock equivalents	632,992	597,246	259,323
Common Stock Options
Potentially dilutive common stock equivalents:
Total potentially dilutive common stock equivalents	367,600	748,150	775,650
Restricted Stock Units
Potentially dilutive common stock equivalents:
Total potentially dilutive common stock equivalents	209,654	354,058	260,000
Warrants
Potentially dilutive common stock equivalents:
Total potentially dilutive common stock equivalents	1,448,333	1,448,333	1,468,333