Employee Benefit Plans Employee Savings and Stock Ownership Plan (Details) shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2020 USD ($) shares
Retirement Benefits [Abstract]
stock acquired during period shares employee stock ownership plan \| shares	3.3
stock acquired during period value employee stock ownership plan \| $	$ 50.0

stock acquired during period value employee stock ownership plan

No definition available.

Name:	ori_Stockacquiredduringperiodvalueemployeestockownershipplan
Namespace Prefix:	ori_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration