Shareholders' Equity (Share Repurchases) (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	12 Months Ended
	Dec. 26, 2018	Dec. 27, 2017	Dec. 28, 2016
Equity, Class of Treasury Stock [Line Items]
Common stock shares repurchased during the period (shares)	3.9		4.6
Common stock shares repurchased during the period (value in US$)	$ 61,189	$ 82,858	$ 51,771
Share Repurchase Program 2017 [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase, authorized amount (dollars)	200,000
Remaining shares to be repurchased (value in US$)	128,400
Share Repurchase Program 2016 [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase, authorized amount (dollars)		$ 100,000
Accelerated Share Repurchase 2015 [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase, authorized amount (dollars)			$ 50,000
Common stock shares repurchased during the period (shares)			1.5
Common stock shares repurchased during the period (value in US$)			$ 13,100
Volume-weighted average price			$ 9.90
Accelerated Share Repurchase 2016 [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase, authorized amount (dollars)			$ 25,000
Common stock shares repurchased during the period (shares)		0.5	1.5
Common stock shares repurchased during the period (value in US$)		$ 6,900	$ 18,100
Volume-weighted average price		$ 12.36
Remaining shares to be repurchased (value in US$)			$ 6,900
Accelerated Share Repurchase 2018 [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase, authorized amount (dollars)	$ 25,000
Common stock shares repurchased during the period (shares)	1.1
Common stock shares repurchased during the period (value in US$)	$ 18,200
Remaining shares to be repurchased (value in US$)	$ 6,800