Net Income per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended					9 Months Ended		12 Months Ended
		Sep. 29, 2018	Dec. 31, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Sep. 29, 2018	Sep. 30, 2017	Dec. 31, 2017
Earnings Per Share, Diluted [Line Items]
Net income attributable to shareholders		$ 176,533	$ 53,653	$ 134,064	$ 99,722	$ 114,737	$ 485,542	$ 348,523	$ 402,176
Weighted average shares outstanding - basic		87,602		88,453			87,785	88,870
Net effect of various dilutive stock-based compensation awards		1,006		1,087			974	1,066
Weighted average shares outstanding - diluted		88,608		89,540			88,759	89,936
Net income per share:
Basic		$ 2.02		$ 1.52			$ 5.53	$ 3.92
Diluted	[1]	$ 1.99		$ 1.50			$ 5.47	$ 3.88
Stock Compensation Plan [Member]
Net income per share:
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		582		396			540	363

[1] Stock-based compensation awards for the issuance of 582 and 540 shares for the third quarter and first nine months of 2018 and 396 and 363 shares for the third quarter and first nine months of 2017, respectively, were excluded from the computation of net income per share on a diluted basis as their effect was anti-dilutive.