Unaudited Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2017		Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	[1]	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	[2]	Dec. 31, 2015	[2]
Quarterly Financial Data [Abstract]
Revenue	$ 71,780	[1]	$ 66,087	$ 72,413	$ 69,454	$ 67,451		$ 71,315	$ 66,918	$ 64,789	$ 279,734	$ 270,473		$ 257,865
Net income	7,459	[1]	1,458	19,052	3,041	354		3,917	2,922	2,224	31,010	9,417		23,031
Net income attributable to RDI shareholders	$ 7,382	[1]	$ 1,556	$ 19,032	$ 3,029	$ 352		$ 3,855	$ 2,970	$ 2,226	$ 30,999	$ 9,403		$ 23,110
Basic earnings per share	$ 0.33	[1]	$ 0.07	$ 0.82	$ 0.13	$ 0.01		$ 0.17	$ 0.13	$ 0.09	$ 1.35	$ 0.40		$ 0.99
Diluted earnings per share	$ 0.32	[1]	$ 0.07	$ 0.81	$ 0.13	$ 0.02		$ 0.16	$ 0.13	$ 0.09	$ 1.33	$ 0.40		$ 0.98
Net tax benefit from non-recurring items of tax benefit and expense	$ 2,500

[1] Net income for the 4th quarter of 2017 includes approximately $2.5 million net tax benefit from non-recurring items of tax benefit and expense related to the Tax Cuts and Jobs Act enacted December 2017 and dissolution of a non-operating foreign subsidiary.

[2] Certain prior year balances have been reclassified to conform to the 2017 presentation (see Note 2 - Summary of Significant Accounting Policies - Reclassifications).