v3.8.0.1
Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($)
$ in Thousands
Sep. 30, 2017
Dec. 31, 2016
Assets:    
Total assets $ 35,037 $ 35,014
Liabilities:    
Restructuring liability 3,527 0
Total liabilities 3,527 0
Money market mutual funds    
Assets:    
Cash and cash equivalents, fair value disclosure 17,755 17,637
Certificates of deposit    
Assets:    
Cash and cash equivalents, fair value disclosure 17,282 17,377
Level 1    
Assets:    
Total assets 35,037 35,014
Liabilities:    
Restructuring liability 0 0
Total liabilities 0 0
Level 1 | Money market mutual funds    
Assets:    
Cash and cash equivalents, fair value disclosure 17,755 17,637
Level 1 | Certificates of deposit    
Assets:    
Cash and cash equivalents, fair value disclosure 17,282 17,377
Level 2    
Assets:    
Total assets 0 0
Liabilities:    
Restructuring liability 0 0
Total liabilities 0 0
Level 2 | Money market mutual funds    
Assets:    
Cash and cash equivalents, fair value disclosure 0 0
Level 2 | Certificates of deposit    
Assets:    
Cash and cash equivalents, fair value disclosure 0 0
Level 3    
Assets:    
Total assets 0 0
Liabilities:    
Restructuring liability 3,527 0
Total liabilities 3,527 0
Level 3 | Money market mutual funds    
Assets:    
Cash and cash equivalents, fair value disclosure 0 0
Level 3 | Certificates of deposit    
Assets:    
Cash and cash equivalents, fair value disclosure $ 0 $ 0