Description of Business and Summary of Significant Accounting Policies (Anti-dilutive) (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Anti-dilutive weighted-average common stock equivalents excluded from the calculation of diluted net income per share
Total (in shares)	192	1,111	179	1,319
Options | Common Stock
Anti-dilutive weighted-average common stock equivalents excluded from the calculation of diluted net income per share
Total (in shares)		1,096		1,310
Restricted stock units
Anti-dilutive weighted-average common stock equivalents excluded from the calculation of diluted net income per share
Total (in shares)	192	15	179	9