Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Weighted Average Shares and Share Equivalents Used to Calculate Basic and Diluted Earnings Per Share

The following weighted average shares and share equivalents were used to calculate basic and diluted earnings per share for the years ended December 31, 2017, 2016 and 2015:

	Year Ended December 31,
	2017	2016	2015
Weighted average number of shares outstanding used to    calculate basic EPS	3,733	3,847	4,022
Dilutive securities:
Stock options and restricted share units	507	257	233
Weighted average number of shares and share equivalents outstanding used to calculate diluted EPS	4,240	4,104	4,255

Summary of Antidilutive Securities Excluded from Computation of Earnings Per Share

The following stock options issued under equity incentive plans were outstanding during the years ended December 31, 2017, 2016 and 2015, but were not included in the computation of diluted earnings per share because the effect would have been anti-dilutive.

	Year Ended December 31,
	2017	2016	2015
Anti-dilutive securities	15	87	50