Equity Incentive Plans - Options Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summary of the activity of stock option awards, shares
Options outstanding, Beginning Balance , Shares	1,230
Options granted, shares	475	500	300
Options exercised, Shares	(103)
Options forfeited/canceled, Shares	(140)
Options outstanding, Ending Balance , Shares	1,462	1,230
Options vested and expected to vest, Shares	1,386
Options exercisable, Shares	646
Summary of the activity of stock option awards, weighted average exercise price
Options outstanding, Beginning Balance, Wtd. Avg. Exercise Price (in dollars per share)	$ 25.02
Options granted, Wtd. Avg. Exercise Price (in dollars per share)	21.60
Options exercised, Wtd. Avg. Exercise Price (in dollars per share)	19.07
Options forfeited/canceled/expired, Wtd. Avg. Exercise Price (in dollars per share)	25.32
Options outstanding, Ending Balance, Wtd. Avg. Exercise Price (in dollars per share)	24.30	$ 25.02
Options vested and expected to vest, Wtd. Average Exercise Price (in dollars per share)	24.31
Options exercisable, Wtd. Avg. Exercise Price (in dollars per share)	$ 23.81
Options outstanding, Ending Balance, Wtd. Avg. Remaining Contractual Term	7 years 2 months 11 days	7 years 3 months 29 days
Options vested and expected to vest, Wtd. Avg Remaining Contractual Term	7 years 1 month 9 days
Options exercisable, Wtd. Avg. Remaining Contractual Term	5 years 7 months 4 days
Options outstanding, Beginning Balance, Average Intrinsic Value	$ 924	$ 3,117
Options vested and expected to vest, Aggregate Intrinsic Value	923
Options exercisable, Aggregate Intrinsic Value	910
Intrinsic value of options exercised	519	4,126	$ 1,671
Fair value of shares vested	$ 794	$ 373	$ 518