Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Earnings (Deficit) [Member]	Accumulated Other Comprehensive Income ( Loss ) Retirement Benefit Obligations [Member]	Accumulated Other Comprehensive Income ( Loss ) Interest Rate Swaps [Member]	Accumulated Other Comprehensive Income ( Loss ) Total [Member]
BEGINNING BALANCE at Dec. 27, 2014	$ 1,622,032	$ 1,667	$ 2,292,178	$ (513,772)	$ (158,041)		$ (158,041)
BEGINNING BALANCE (in shares) at Dec. 27, 2014		166,667,000
Settlements/reclassifications of Redeemable common stock	(8,091)		(8,091)
Share-based compensation expense	8,055		8,055
Changes in retirement benefit obligations, net of income tax	83,663				83,663		83,663
Net income	167,518			167,518
ENDING BALANCE at Jan. 02, 2016	1,873,177	$ 1,667	2,292,142	(346,254)	(74,378)		(74,378)
ENDING BALANCE (in shares) at Jan. 02, 2016		166,667,000
Settlements/reclassifications of Redeemable common stock	43,111	$ 25	43,086
Settlements/reclassifications of Redeemable common stock (in shares)		2,522,000
Share-based compensation expense	14,856		14,856
Net proceeds from initial public offering	1,113,799	$ 511	1,113,288
Net proceeds from initial public offering (in shares)		51,111,000
Cash distribution to shareholders ($3.94 per share - Note 14)	(666,332)		(666,332)
Proceeds from employee share purchase plan	3,354	$ 2	3,352
Proceeds from employee share purchase plan (in shares)		174,000
Share-based awards vested/exercised of stock options		$ 4	(4)
Share-based awards vested/exercised of stock options (in shares)		459,000
Common stock and share-based awards settled	(9,124)		(9,124)
Common stock and share-based awards settled (in shares)		(4,000)
Changes in retirement benefit obligations, net of income tax	(44,985)				(44,985)		(44,985)
Net income	209,794			209,794
ENDING BALANCE at Dec. 31, 2016	2,537,650	$ 2,209	2,791,264	(136,460)	(119,363)		(119,363)
ENDING BALANCE (in shares) at Dec. 31, 2016		220,929,000
Share-based compensation expense	19,908		19,908
Proceeds from employee share purchase plan	15,810	$ 7	15,803
Proceeds from employee share purchase plan (in shares)		645,000
Share-based awards vested/exercised of stock options	$ 18,386	$ 17	18,369
Share-based awards vested/exercised of stock options (in shares)	4,778,199	1,676,000
Net share-settled stock options		$ 12	(12)
Net share-settled stock options (in shares)		1,192,000
Vested restricted stock units-net		$ 3	(3)
Vested restricted stock units-net (in shares)		280,000
Performance restricted shares-net		$ 2	(2)
Performance restricted shares-net (in shares)		241,000
Tax withholding payments for net share-settled equity awards	$ (28,293)		(28,293)
Common stock repurchased	(280,000)	$ (100)	(95,580)	(184,320)
Common stock repurchased (in shares)		(10,000,000)
Changes in retirement benefit obligations, net of income tax	16,171				16,171		16,171
Unrecognized gain on interest rate swaps, net of income tax	7,437					$ 7,437	7,437
Net income	444,294			444,294
ENDING BALANCE at Dec. 30, 2017	$ 2,751,363	$ 2,150	$ 2,721,454	$ 123,514	$ (103,192)	$ 7,437	$ (95,755)
ENDING BALANCE (in shares) at Dec. 30, 2017		214,963,000