Shareholders' Equity (Narrative) (Details) - USD ($)		12 Months Ended
	Jul. 29, 2016	Dec. 31, 2016
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, repurchased cost		$ 43,800,000
Common Stock [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, expiration date	Jul. 31, 2018
Shares repurchase program, shares repurchased		1,111,525
Shares repurchase program, repurchased cost		$ 43,800,000
Shares repurchase program, average price per share		$ 39.45
Common Stock [Member] | Maximum [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, authorized amount	$ 150,000,000