Capital Stock - Captial Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Equity [Abstract]
Percent of entity owned by current and retired employees			100.00%
Percent of entity held in voting trust	84.00%		84.00%
Common, stated value (in dollars per share)	$ 20		$ 20		$ 20
Dividends, Common Stock, Cash	$ 4,985	$ 4,802	$ 14,962	$ 14,418