Share-Based Compensation - Share-Based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 29, 2013	Jun. 30, 2012	Jun. 29, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 1.8	$ 1.4	$ 2.5	$ 2.2
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	0.3	0.1	0.4	0.2
Directors' Share Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	0.8	0.7	0.8	0.7
Performance-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	0.2	0.2	0.4	0.2
Time-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 0.5	$ 0.4	$ 0.9	$ 1.1