Stockholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2015		Sep. 30, 2015	[2]	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	[4]	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 09, 2015	Dec. 04, 2013
Class of Stock [Line Items]
Common Stock, Shares Authorized	20,000,000						20,000,000						20,000,000	20,000,000
Common Stock, Shares, Issued	11,115,779						11,115,779						11,115,779	11,115,779
Common Stock, Par or Stated Value Per Share	$ 0.01						$ 0.01						$ 0.01	$ 0.01
Common Stock, Dividends, Per Share, Cash Paid	$ 0.04	[1]	$ 0.04		$ 0.04	$ 0.04	$ 0.04	[3]	$ 0.03	$ 0.03		$ 0.03	$ 0.16	$ 0.13	$ 0.12
Treasury Stock, Shares, Acquired													80,512
Treasury Stock, Value, Acquired, Cost Method													$ 1,587
Payments for Repurchase of Common Stock													$ 2,701	$ 985	$ 708
Stock Repurchase Program Expiration Date													Dec. 31, 2017
Shares Paid for Tax Withholding for Share Based Compensation													25,340	21,676
Adjustments Related to Tax Withholding for Share-based Compensation													$ 1,114	$ 985
Dividends, Common Stock, Cash													$ 1,656	$ 1,345	$ 1,240
Common Stock [Member]
Class of Stock [Line Items]
Common Stock, Shares Authorized	20,000,000						20,000,000						20,000,000	20,000,000
Common Stock, Shares, Issued	11,115,779						11,115,779						11,115,779	11,115,779
Common Stock, Par or Stated Value Per Share	$ 0.01												$ 0.01
Treasury Stock, Shares, Acquired													80,512
Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	5,000,000												5,000,000
Preferred Stock, Shares Issued	0												0
Preferred Stock, No Par Value	$ 0.00												$ 0.00
December 2013 Share Repurchase Program [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount																	$ 15,000
December 2015 Share Repurchase Program [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount																$ 30,000

[1] Fourth quarter 2015 includes $2,279 pre-tax gain on sale of Tucson, AZ concrete tie facility.

[2] Third quarter 2015 includes $80,337 ($63,887 net of tax) impairment of goodwill related to the IOS and Chemtec reporting units.

[3] Fourth quarter 2014 includes a $4,766 warranty charge related to UPRR warranty claim.

[4] Second quarter 2014 includes a $4,000 warranty charge related to UPRR warranty claim.