Summary of Significant Accounting Policies and New Accounting Pronouncements - Environmental Costs (Details)	12 Months Ended
Dec. 31, 2017
Accounting Policies [Abstract]
Environmental loss contingencies term	20 years

Estimated time frame for probable costs expected to be incurred for environmental liabilities.

No definition available.

Name:	ryam_EnvironmentalLossContingenciesTerm
Namespace Prefix:	ryam_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration