Accumulated Other Comprehensive Income (Loss) and Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2016	Mar. 31, 2016
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	$ (4,267)		$ (5,000)
Cash dividends per common share (in dollars per share)	$ 0.845	$ 0.815
Common Stock
Class of Stock [Line Items]
Repurchased common stock (in shares)	1,300,936	608,500
Repurchased common stock, value	$ 52,900	$ 30,400
Stock repurchase program, remaining authorized repurchase amount	84,000
Interest rate swap
Class of Stock [Line Items]
Derivative, notional amount				$ 150,000
Derivative, fixed interest rate				1.29%
Derivative liability	2,200
Accumulated other comprehensive income (loss)	$ 1,400