Share-based compensation Additional Information (Details)	12 Months Ended
Dec. 31, 2012 optionplans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Optin Plans	2
Percentage of Fair Market Value	110.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Contractual Term	10 years

Share-based Compensation Arrangement by Share-based Payment Award, Specific Employee Grants, Award Exercise Price as Percentage of Market Value

No definition available.

Name:	spir_ShareBasedCompensationArrangementByShareBasedPaymentAwardSpecificEmployeeGrantsAwardExercisePriceAsPercentageOfMarketValue
Namespace Prefix:	spir_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant