Annual report pursuant to Section 13 and 15(d)

Stock Option and Purchase Plans - Fair Value for Options Granted under Employee Stock Purchase Plan (Detail)

v3.6.0.2
Stock Option and Purchase Plans - Fair Value for Options Granted under Employee Stock Purchase Plan (Detail)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]      
Dividend Yield 0.00% 0.00% 0.00%
Employee Stock      
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]      
Risk-free Interest Rate 0.63% 0.31% 0.10%
Dividend Yield 0.00% 0.00% 0.00%
Volatility Factor 0.45% 0.40% 0.42%
Expected Life in Years 1 year 1 year 1 year