Employee Stock Benefit Plans (Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding balance at beginning of period	656,671	834,010	988,780
Granted	351,590	108,297	233,054
Exercised	(100,813)	(241,122)	(363,459)
Canceled	(262,225)	(44,514)	(24,365)
Outstanding balance at end of period	645,223	656,671	834,010	988,780
Exercisable balance at end of period	300,288
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, weighted-average exercise price, balance at beginning of period (in USD per share)	$ 21.22	$ 17.28	$ 14.07
Granted, weighted-average exercise price (in USD per share)	17.23	36.90	23.92
Exercised, weighted-average exercise price (in USD per share)	13.90	13.85	12.57
Canceled, weighted-average exercise price (in USD per share)	23.73	25.43	20.58
Outstanding, weighted-average exercise price, balance at end of period (in USD per share)	$ 19.17	$ 21.22	$ 17.28	$ 14.07
Outstanding, weighted-average remaining contractual life	6 years 7 months 24 days	6 years 10 months 2 days	6 years 7 months 28 days	5 years
Outstanding, aggregate intrinsic value	$ 1,407	$ 2,103	$ 11,808	$ 6,856
Exercised, aggregate intrinsic value	$ 379	$ 5,722	$ 5,218
Exercisable balance at end of period, weighted-average exercise price (in USD per share)	$ 18.43
Exercisable, weighted average remaining contractual life	4 years 3 months 26 days
Exercisable, aggregate intrinsic value	$ 816