v3.22.2.2
Cover Page Cover Page
Jul. 29, 2020
Cover [Abstract]  
Document Type 8-K
Document Period End Date Dec. 08, 2022
Entity Registrant Name Columbia Financial, Inc.
Entity Incorporation, State or Country Code DE
Entity File Number 001-38456
Entity Tax Identification Number 22-3504946
Entity Address, Address Line One 19-01 Route 208 North
Entity Address, City or Town Fair Lawn
Entity Address, State or Province NJ
Entity Address, Postal Zip Code 07410
City Area Code 800
Local Phone Number 522-4167
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common stock, $0.01 par value per share
Trading Symbol CLBK
Security Exchange Name NASDAQ
Entity Emerging Growth Company false
Amendment Flag false
Entity Central Index Key 0001723596