Document and Entity Information shares in Millions	3 Months Ended
	Mar. 31, 2018 shares
Document and Entity Information [Abstract]
Entity Registrant Name	SERVICENOW, INC.
Trading Symbol	NOW
Entity Central Index Key	0001373715
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	176.6