XML 61 R47.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stock-Based Compensation and Employee Benefit Plans - Weighted-Average Assumptions for Non Performance-Based Fair Value for Stock Options (Detail) - Non Performance-Based Stock Options [Member]
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Vicor [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Risk-free interest rate 2.10% 1.50% 2.00%
Expected dividend yield 0.00% 0.00% 0.00%
Expected volatility 43.00% 45.00% 51.00%
Expected lives (years) 7 years 1 month 6 days 7 years 2 months 12 days 7 years 2 months 12 days
VI Chip [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Risk-free interest rate 1.90% 1.70% 2.10%
Expected dividend yield 0.00% 0.00% 0.00%
Expected volatility 32.00% 34.00% 37.00%
Expected lives (years) 6 years 6 months 6 years 6 months 6 years 6 months
Picor [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Risk-free interest rate 1.90% 1.50% 1.90%
Expected dividend yield 0.00% 0.00% 0.00%
Expected volatility 48.00% 42.00% 41.00%
Expected lives (years) 6 years 6 months 6 years 6 months 6 years 6 months