Non-controlling interests (Details) - USD ($) $ in Millions		3 Months Ended
		Apr. 02, 2017	Apr. 03, 2016
Noncontrolling Interest [Line Items]
Balance	[1]	$ 1,030.9
Net income		35.6	$ 34.8
Other comprehensive income (loss)		14.3	$ 11.2
Dividends declared		(1.7)
Dividends to non-controlling interest		(0.2)
Issuance of shares pursuant to employee stock compensation plans		2.2
Stock based compensation		0.6
Balance	[2]	1,081.8
Common Stock [Member]
Noncontrolling Interest [Line Items]
Balance		4.8
Net income		0.0
Other comprehensive income (loss)		0.0
Dividends declared		0.0
Dividends to non-controlling interest		0.0
Issuance of shares pursuant to employee stock compensation plans		0.0
Stock based compensation		0.0
Balance		4.8
Additional Paid-in Capital [Member]
Noncontrolling Interest [Line Items]
Balance		400.0
Net income		0.0
Other comprehensive income (loss)		0.0
Dividends declared		0.0
Dividends to non-controlling interest		0.0
Issuance of shares pursuant to employee stock compensation plans		2.2
Stock based compensation		0.6
Balance		402.8
Retained Earnings [Member]
Noncontrolling Interest [Line Items]
Balance		1,419.1
Net income		34.6
Other comprehensive income (loss)		0.0
Dividends declared		(1.7)
Dividends to non-controlling interest		0.0
Issuance of shares pursuant to employee stock compensation plans		0.0
Stock based compensation		0.0
Balance		1,452.0
Accumulated Other Comprehensive Income (Loss) [Member]
Noncontrolling Interest [Line Items]
Balance		(221.1)
Net income		0.0
Other comprehensive income (loss)		13.8
Dividends declared		0.0
Dividends to non-controlling interest		0.0
Issuance of shares pursuant to employee stock compensation plans		0.0
Stock based compensation		0.0
Balance		(207.3)
Treasury Stock [Member]
Noncontrolling Interest [Line Items]
Balance		(596.3)
Net income		0.0
Other comprehensive income (loss)		0.0
Dividends declared		0.0
Dividends to non-controlling interest		0.0
Issuance of shares pursuant to employee stock compensation plans		0.0
Stock based compensation		0.0
Balance		(596.3)
Non-controlling Interests [Member]
Noncontrolling Interest [Line Items]
Balance		24.4
Net income		1.0
Other comprehensive income (loss)		0.6
Dividends declared		0.0
Dividends to non-controlling interest		(0.2)
Issuance of shares pursuant to employee stock compensation plans		0.0
Stock based compensation		0.0
Balance		$ 25.8

[1] Condensed from audited financial statements

[2] Unaudited