Employee Retirement Plans (Schedule of Contributions Made by the Company to Each Multiemployer Plan) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Contributions	$ 296	$ 333	$ 329
National Integrated Group Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions	218	246	233
Sheet Metal Workers National Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions	50	56	61
Sheet Metal Workers Pension Plan Of Northern California [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions	$ 28	$ 31	$ 35