Summary of Significant Accounting Policies and New Accounting Pronouncements - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2016	Mar. 25, 2016	Dec. 25, 2015	Sep. 25, 2015	Jun. 30, 2015	Mar. 27, 2015	Dec. 26, 2014	Sep. 26, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Accounting Policies [Abstract]
Net income (loss) applicable to TRC Companies, Inc.	$ 5,909	$ (14,297)	$ 3,937	$ 4,492	$ 6,763	$ 5,165	$ 4,002	$ 3,485	$ 41	$ 19,415	$ 12,051
Basic weighted-average common shares outstanding (in shares)									30,936	30,291	29,594
Effect of dilutive stock options and restricted stock (in shares)									423	433	546
Diluted weighted-average common shares outstanding (in shares)									31,359	30,724	30,140
Basic earnings (loss) per common share (in dollars per share)	$ 0.19	$ (0.46)	$ 0.13	$ 0.15	$ 0.22	$ 0.17	$ 0.13	$ 0.12	$ 0.00	$ 0.64	$ 0.41
Diluted earnings (loss) per common share (in dollars per share)	$ 0.19	$ (0.46)	$ 0.13	$ 0.14	$ 0.22	$ 0.17	$ 0.13	$ 0.11	$ 0.00	$ 0.63	$ 0.40
Anti-dilutive stock-based awards excluded from the calculation (in shares)									1,463	1,610	2,004