Document and Entity Information	3 Months Ended
	Mar. 31, 2019 shares
Document and Entity Information
Entity Registrant Name	SIMPSON MANUFACTURING CO INC /CA/
Entity Central Index Key	0000920371
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	44,661,907
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Small Business	false
Entity Emerging Growth Company	false