Common Stock (Details) shares in Thousands	Dec. 31, 2016 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares reserved for issuance (in shares)	7,530
Reserved Under Stock Option Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares reserved for issuance (in shares)	4,030
Reserved Under Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares reserved for issuance (in shares)	3,500