Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income ( Loss ) Retirement Benefit Obligation [Member]
BEGINNING BALANCE at Dec. 28, 2013	$ 1,843,764	$ 1,667	$ 2,285,634	$ (440,858)	$ (2,679)
BEGINNING BALANCE (in shares) at Dec. 28, 2013		166,667,000
Settlements/reclassifications of Redeemable common stock	(23)		(23)
Share-based compensation expense	6,567		6,567
Changes in retirement benefit obligations, net of income tax	(155,362)				(155,362)
Net income (loss)	(72,914)			(72,914)
ENDING BALANCE at Dec. 27, 2014	1,622,032	$ 1,667	2,292,178	(513,772)	(158,041)
ENDING 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
Net income (loss)	167,518			167,518
ENDING BALANCE at Jan. 02, 2016	1,873,177	$ 1,667	2,292,142	(346,254)	(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		$ 4	(4)
Share-based awards vested/exercised (in shares)	808,164	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)
Net income (loss)	209,794			209,794
ENDING BALANCE at Dec. 31, 2016	$ 2,537,650	$ 2,209	$ 2,791,264	$ (136,460)	$ (119,363)
ENDING BALANCE (in shares) at Dec. 31, 2016		220,929,000