STOCK-BASED COMPENSATION - Weighted-average Assumptions (Details) - $ / shares |
3 Months Ended | 6 Months Ended | ||
---|---|---|---|---|
Jun. 30, 2016 |
Jun. 30, 2015 |
Jun. 30, 2016 |
Jun. 30, 2015 |
|
Option Awards | ||||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
Average risk-free interest rate | 1.20% | 1.40% | 1.20% | 1.40% |
Expected dividend yield | 0.00% | 0.00% | 0.00% | 0.00% |
Expected volatility (as a percent) | 33.10% | 29.70% | 33.10% | 29.80% |
Expected term, period | 4 years 6 months | 4 years 6 months | 4 years 6 months | 4 years 6 months |
Fair value, per option or share (in dollars per share) | $ 31.08 | $ 17.70 | $ 30.99 | $ 17.82 |
ESPP | ||||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
Average risk-free interest rate | 0.30% | 0.20% | 0.30% | 0.20% |
Expected dividend yield | 0.00% | 0.00% | 0.00% | 0.00% |
Expected volatility (as a percent) | 32.80% | 26.50% | 29.00% | 27.60% |
Expected term, period | 7 months 6 days | 7 months 6 days | 7 months 6 days | 7 months 6 days |
Fair value, per option or share (in dollars per share) | $ 24.92 | $ 16.51 | $ 20.85 | $ 15.43 |