XML 99 R80.htm IDEA: XBRL DOCUMENT v3.3.1.900
Common Stock - Assumptions Used for Calculating Fair Values of Stock Option Awards (Detail) - $ / shares
1 Months Ended 12 Months Ended
Dec. 31, 1999
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Stock Options Granted        
Weighted average grant date fair value, per share (in dollars per share)     $ 26.46 $ 19.84
Weighted average assumptions used:        
Expected volatility   0.00% 52.80% 66.40%
Expected lives (in years) 3 years 1 day 5 years 4 years 10 months 24 days
Risk-free interest rates   0.00% 1.70% 0.80%
Dividends yields   0.00% 0.00% 0.00%