Capital Stock - Captial Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 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	83.00%		83.00%
Common, stated value (in dollars per share)	$ 20		$ 20		$ 20
Dividends, Common Stock, Cash	$ 4,994	$ 4,801	$ 9,977	$ 9,616