Equity Incentive Plans (Options Activity) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of the activity of stock option awards, shares
Options outstanding, Beginning Balance , Shares	1,211
Options granted, shares	462	300	300
Options exercised, Shares	(360)
Options forfeited/canceled/expired, Shares	(83)
Options outstanding, Ending Balance , Shares	1,230	1,211
Options vested and expected to vest, Shares	1,165
Options exercisable, Shares	523
Summary of the activity of stock option awards, weighted average exercise price
Options outstanding, Beginning Balance, Wtd. Avg. Exercise Price (in dollars per share)	$ 20.65
Options granted, Wtd. Avg. Exercise Price (in dollars per share)	32.30
Options exercised, Wtd. Avg. Exercise Price (in dollars per share)	19.11
Options forfeited/canceled/expired, Wtd. Avg. Exercise Price (in dollars per share)	27.41
Options outstanding, Ending Balance, Wtd. Avg. Exercise Price (in dollars per share)	25.02	$ 20.65
Options vested and expected to vest, Wtd. Average Exercise Price (in dollars per share)	24.84
Options exercisable, Wtd. Avg. Exercise Price (in dollars per share)	$ 22.04
Options outstanding, Ending Balance, Wtd. Avg. Remaining Contractual Term	7 years 3 months 30 days	7 years 1 month 21 days
Options vested and expected to vest, Wtd. Avg Remaining Contractual Term	7 years 2 months 29 days
Options exercisable, Wtd. Avg. Remaining Contractual Term	5 years 10 months 35 days
Options outstanding, Beginning Balance, Average Intrinsic Value	$ 3,117	$ 5,466
Options vested and expected to vest, Aggregate Intrinsic Value	3,042
Options exercisable, Aggregate Intrinsic Value	2,174
Intrinsic value of options exercised	4,126	1,671	$ 2,000
Fair value of shares vested	$ 373	$ 518	$ 1,314