Cover - shares	6 Months Ended
	Jun. 30, 2024	Jul. 31, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2024
Document Transition Report	false
Entity File Number	001-34582
Entity Registrant Name	NORTHWEST BANCSHARES, INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	27-0950358
Entity Address, Address Line One	3 Easton Oval
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Columbus
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	43219
City Area Code	814
Local Phone Number	726-2140
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.01 Par Value
Trading Symbol	NWBI
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		127,371,199
Entity Central Index Key	0001471265
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2