Fair Value Measurements (Narrative) (Details) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value Measurements [Abstract]
Transfers of assets and liabilities between level 1, 2, 3	$ 0	$ 0	$ 0	$ 0

Amount of transfers of financial instruments classified in shareholders' equity measured on a recurring basis betwee level 1, 2, 3 of the fair value hierarchy.

No definition available.

Name:	rdi_FairValueEquityBetweenLevelsOneTwoThreeTransfersAmount
Namespace Prefix:	rdi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration