Share Plans (Tables)

12 Months Ended

Dec. 27, 2019

Share-based Payment Arrangement [Abstract]

Maximum Number of Common Shares to be Issued as Awards

The maximum number of common shares to be issued as Awards, subject to adjustment as provided under the terms of the respective plans were as follows:

	Maximum Number of Common Shares to be Issued as Awards (in millions)
2013 Plan	5.7
2015 Plan	17.8
2018 Plan	26.8

Schedule of Share Option Activity

Share option activity and information was as follows:

	Share Options		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding as of December 30, 2016	3,386,694		$	61.24
Granted	1,719,532		51.57
Exercised	(113,605	)	47.74
Expired/Forfeited	(348,637	)	68.08
Outstanding as of December 29, 2017	4,643,984		57.78
Granted	3,159,521		13.92
Exercised	(39,949	)	32.00
Expired/Forfeited	(756,505	)	52.63
Outstanding as of December 28, 2018	7,007,051		38.74
Granted	1,378,175		22.09
Exercised	(45,324	)	20.67
Expired/Forfeited	(1,449,202	)	34.80
Outstanding as of December 27, 2019	6,890,700		36.39		1.6	$	—
Vested and non-vested expected to vest as of December 27, 2019	6,376,302		37.58		7.1	$	—
Exercisable as of December 27, 2019	3,349,227		49.80		1.2	—

Schedule of the Valuation Assumptions Used in the Conversion

The weighted-average assumptions used in the Black-Scholes pricing model for shares granted in fiscal 2019, 2018 and 2017, along with the weighted-average grant-date fair value, were as follows:

	Fiscal Year
	2019			2018			2017
Expected share price volatility	45.8		%	38.2		%	36.0		%
Risk-free interest rate	2.2		%	2.6		%	2.0		%
Expected annual dividend per share	—		%	—		%	—		%
Expected life of options (in years)	5.3			5.3			5.3
Fair value per option	$	9.66		$	5.32		$	18.36

Schedule of Restricted Share Unit Activity

RSU activity was as follows:

	Shares		Weighted-Average Grant-Date Fair Value
Non-vested as of December 30, 2016	883,462		$	71.03
Granted	655,282		50.74
Exercised	(263,189	)	69.14
Expired/Forfeited	(169,789	)	68.57
Non-vested as of December 29, 2017	1,105,766		60.08
Granted	1,222,568		14.58
Exercised	(433,354	)	57.93
Expired/Forfeited	(209,879	)	44.38
Non-vested as of December 28, 2018	1,685,101		29.54
Granted	755,180		20.13
Exercised	(713,274	)	35.29
Expired/Forfeited	(307,987	)	24.81
Non-vested as of December 27, 2019	1,419,020		22.68

Share-based Compensation, Performance Shares Award Outstanding Activity

PSU activity was as follows ⁽¹⁾:

	Shares		Weighted-Average Grant-Date Fair Value
Non-vested as of December 30, 2016	265,648		$	88.51
Granted	348,963		51.73
Forfeited	(48,606	)	107.00
Vested	(61,554	)	62.65
Non-vested as of December 29, 2017	504,451		64.44
Granted	770,714		13.80
Forfeited	(89,614	)	59.18
Vested	(24,022	)	98.27
Non-vested as of December 28, 2018	1,161,529		28.61
Granted	448,363		32.46
Forfeited	(414,387	)	30.54
Non-vested as of December 27, 2019	1,195,505		23.85

(1)    The number of shares disclosed within this table are at the target number of 100.0%.

Schedule of Share-based Payment Award, Performance Share Awards, Valuation Assumptions

The assumptions used in the Monte Carlo model for PSUs granted during each year were as follows:

	Fiscal Year
	2019		2018		2017
Expected stock price volatility	55.2	%	56.9	%	47.5	%
Peer group stock price volatility	41.3	%	39.1	%	39.9	%
Correlation of returns	47.8	%	2.1	%	17.0	%

Share-based Payment Arrangement, Restricted Stock Unit, Activity

The grant-date fair value of RSAs, adjusted for estimated forfeitures, was recognized as expense on a straight-line basis over the service period. The weighted average grant-date fair value per share was $70.88.

	Shares
Non-vested as of December 30, 2016	14,868
Vested	(7,970	)
Forfeited	(2,223	)
Non-vested as of December 29, 2017	4,675
Vested	(3,970	)
Forfeited	(705	)
Non-vested as of December 28, 2018	—