Stock-based Compensation Plans (Assumptions used in Black-Scholes Model) (Details) - Forcepoint - $ / shares |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Unit Price | $ 1,508.01 | $ 1,101.31 | $ 935.28 |
| Expected life (in years) | 3 years 3 days | 2 years 3 months 14 days | 4 years 2 months 26 days |
| Expected unit price volatility | 43.66% | 49.51% | 54.65% |
| Risk free interest rate | 2.69% | 1.46% | 1.12% |
| Dividend yield | 0.00% | 0.00% | 0.00% |
| Grant date fair value | $ 486.94 | $ 339.72 | $ 402.64 |