Employee Stock Benefit Plans (Stock Appreciation Right Activity) (Details) - Stock Appreciation Rights (SARs) - 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, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding balance at beginning of period	244,229	244,229	250,979
Granted	0	0	2,600
Exercised			(6,475)
Canceled			(2,875)
Outstanding balance at end of period	244,229	244,229	244,229	250,979
Exercisable balance at end of period	243,079
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, weighted-average exercise price, balance at beginning of period (in USD per share)	$ 21.27	$ 21.27	$ 21.07
Granted, weighted-average exercise price (in USD per share)			23.02
Exercised, weighted-average exercise price (in USD per share)			14.98
Canceled, weighted-average exercise price (in USD per share)			16.99
Outstanding, weighted-average exercise price, balance at end of period (in USD per share)	$ 21.27	$ 21.27	$ 21.27	$ 21.07
Outstanding, weighted-average remaining contractual life	1 month 13 days	8 years	9 years	10 years
Outstanding, aggregate intrinsic value	$ 4	$ 14	$ 2,483	$ 0
Share-based Compensation Arrangement By Share-based Payment Award, Non-option Equity Instruments, Exercisable, Weighted Average Exercise Price	$ 21.27
Share-based compensation arrangement by share-based payment award, non-option equity instruments, exercisable, weighted average remaining contractual life	1 month 2 days
Share-based Compensation Arrangement By Share-based Payment Award, Non-option Equity Instruments, Exercisable, Intrinsic Value	$ 4