Consolidated Statement of Shareholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Dividends declared per share (in dollars per share)	$ 0.54	$ 0.54	$ 0.52
Tax expense (benefit) on pension liability	$ (95)	$ 113	$ (448)
Retained Deficit [Member]
Dividends declared per share (in dollars per share)	$ 0.54	$ 0.54	$ 0.52
Accumulated Other Comprehensive Income (Loss) [Member]
Tax expense (benefit) on pension liability	$ 95	$ 113	$ 448