Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Condensed Consolidated Statements of Cash Flows [Abstract]
Prepaid expenses and other current assets	$ 5.3	$ 5.3

Prepaid expenses and other current assets representing withholding taxes .

No definition available.

Name:	now_PrepaidExpensesAndOtherCurrentAssetsRepresentingWithholdingTaxes
Namespace Prefix:	now_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant