Retirement Plans - Asset Allocations (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Jan. 02, 2016	Jan. 03, 2015
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	$ 271.9	$ 280.8	$ 302.1
Equity securities, Percentage	100.00%	100.00%
Level 1 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets		$ 0.0
Level 2 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	$ 256.4	269.0
Fair Value, Inputs, Level 3 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	15.5	11.8
Equity securities [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	$ 161.0	$ 169.8
Equity securities, Percentage	59.20%	60.50%
Equity securities [Member] | Level 1 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets		$ 0.0
Equity securities [Member] | Level 2 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	$ 161.0	169.8
Equity securities [Member] | Fair Value, Inputs, Level 3 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets		0.0
Fixed income securities [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	$ 95.7	$ 99.5
Equity securities, Percentage	35.20%	35.40%
Fixed income securities [Member] | Level 1 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets		$ 0.0
Fixed income securities [Member] | Level 2 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	$ 95.4	99.2
Fixed income securities [Member] | Fair Value, Inputs, Level 3 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	0.3	0.3
Other Investments [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	$ 15.2	$ 11.5
Equity securities, Percentage	5.60%	4.10%
Other Investments [Member] | Level 1 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets		$ 0.0
Other Investments [Member] | Level 2 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	$ 0.0	0.0
Other Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Schedule Of Other Postretirement Benefits [Line Items]
Fair value of plan assets	$ 15.2	$ 11.5