Description of Business and Summary of Significant Accounting Policies (Anti-dilutive) (Details) - shares
shares in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Anti-dilutive weighted-average common stock equivalents excluded from the calculation of diluted net income per share      
Total (in shares) 98 665 2,345
Options | Common Stock      
Anti-dilutive weighted-average common stock equivalents excluded from the calculation of diluted net income per share      
Total (in shares)   660 2,328
Restricted stock units      
Anti-dilutive weighted-average common stock equivalents excluded from the calculation of diluted net income per share      
Total (in shares) 98 5 17