Description of Business and Summary of Significant Accounting Policies (Anti-dilutive) (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Anti-dilutive weighted-average common stock equivalents excluded from the calculation of diluted net income per share
Total (in shares)	7	23	122	887
Options | Common Stock
Anti-dilutive weighted-average common stock equivalents excluded from the calculation of diluted net income per share
Total (in shares)		23		881
Restricted stock units
Anti-dilutive weighted-average common stock equivalents excluded from the calculation of diluted net income per share
Total (in shares)	7		122	6