Document And Entity Information	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Oct. 31, 2013
Document And Entity Information [Abstract]
Document Type		10-Q
Amendment Flag		false
Document Period End Date		Sep. 30, 2013
Document Fiscal Year Focus	2013	2013
Document Fiscal Period Focus		Q3
Trading Symbol		zion
Entity Registrant Name		ZIONS BANCORPORATION /UT/
Entity Central Index Key		0000109380
Current Fiscal Year End Date		--12-31
Entity Filer Category		Large Accelerated Filer
Entity Common Stock, Shares Outstanding			184,615,234