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Stockholders' Equity and Stock Plans - Valuation Assumptions (Details)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate 1.67% 2.04% 1.60%
Expected dividend yield on common stock 1.75% 1.70% 1.80%
Expected life in years 6 years 6 years 6 years 9 months 17 days
Expected price volatility 28.06% 30.32% 30.01%