Employee Stock Benefit Plans (Non-Qualified Stock Option Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	249,392	351,590	108,297
Weighted-average grant-date fair value of options granted using the Black-Scholes model	$ 3.00	$ 4.20	$ 14.72
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	249,392	351,590	108,297
Stock option compensation expense included in the Consolidated Statements of Operations	$ 690	$ 705	$ 1,674
Weighted-average grant-date fair value of options granted using the Black-Scholes model	$ 3.00	$ 4.20	$ 14.72
Weighted-average assumptions for stock option grants:
Risk-free interest	2.07%	1.30%	1.68%
Expected term	5 years 9 months 18 days	6 years 3 months 18 days	6 years 4 months 24 days
Expected volatility	38.54%	33.14%	39.92%
Dividend yield	4.32%	2.69%	1.16%