Earnings (Loss) Per Share (Computation Of Basic And Diluted Earnings (Loss) Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2020	[1]	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	[1]	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings (Loss) Per Share [Abstract]
Net income (loss) attributable to RDI common stockholders	$ (17,395)		$ (19,228)	$ (22,702)	$ (5,875)	$ (27,487)		$ 851	$ 2,331	$ (2,124)	$ (65,200)	$ (26,429)	$ 14,034
Weighted average shares of common stock – basic											21,749,155	22,631,754	22,991,277
Weighted average dilutive impact of stock-based awards											466,356	152,368	217,714
Weighted average shares of common stock – diluted											22,215,511	22,784,122	23,208,991
Basic earnings (loss) per share attributable to RDI common stockholders	$ (0.80)		$ (0.88)	$ (1.04)	$ (0.27)	$ (0.99)		$ 0.04	$ 0.10	$ (0.09)	$ (3.00)	$ (1.17)	$ 0.61
Diluted earnings (loss) per share attributable to RDI common stockholders	$ (0.80)		$ (0.88)	$ (1.04)	$ (0.27)	$ (0.99)		$ 0.04	$ 0.10	$ (0.09)	$ (3.00)	$ (1.17)	$ 0.60
Awards excluded from diluted earnings (loss) per share											674,676	516,010	276,681

[1] Since previously published financial statements have been corrected, there is no impact on the fourth quarter results for 2019 or for the full year of 2020 and so no data is displayed here.