Non-controlling interests (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Oct. 02, 2016	Sep. 27, 2015	Oct. 02, 2016	Sep. 27, 2015
Noncontrolling Interest [Line Items]
Balance	[1]			$ 937.7
Net income		$ 42.5	$ 30.3	99.6	$ 93.9
Other comprehensive income (loss)		2.8	$ (34.2)	5.5	$ (61.5)
Dividends declared				(5.2)
Dividends to non-controlling interest				(1.5)
Purchases of common shares				(2.6)
Issuance of shares pursuant to employee stock compensation plans				4.1
Income tax benefit arising from employee stock compensation plans				0.2
Stock based compensation				3.5
Balance	[2]	1,041.3		1,041.3
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
Purchases of common shares				0.0
Issuance of shares pursuant to employee stock compensation plans				0.0
Income tax benefit arising from employee stock compensation plans				0.0
Stock based compensation				0.0
Balance		4.8		4.8
Additional Paid-in Capital [Member]
Noncontrolling Interest [Line Items]
Balance				387.6
Net income				0.0
Other comprehensive income (loss)				0.0
Dividends declared				0.0
Dividends to non-controlling interest				0.0
Purchases of common shares				0.0
Issuance of shares pursuant to employee stock compensation plans				4.1
Income tax benefit arising from employee stock compensation plans				0.2
Stock based compensation				3.5
Balance		395.4		395.4
Retained Earnings [Member]
Noncontrolling Interest [Line Items]
Balance				1,292.7
Net income				96.7
Other comprehensive income (loss)				0.0
Dividends declared				(5.2)
Dividends to non-controlling interest				0.0
Purchases of common shares				0.0
Issuance of shares pursuant to employee stock compensation plans				0.0
Income tax benefit arising from employee stock compensation plans				0.0
Stock based compensation				0.0
Balance		1,384.2		1,384.2
Accumulated Other Comprehensive Income (Loss) [Member]
Noncontrolling Interest [Line Items]
Balance				(180.9)
Net income				0.0
Other comprehensive income (loss)				6.2
Dividends declared				0.0
Dividends to non-controlling interest				0.0
Purchases of common shares				0.0
Issuance of shares pursuant to employee stock compensation plans				0.0
Income tax benefit arising from employee stock compensation plans				0.0
Stock based compensation				0.0
Balance		(174.7)		(174.7)
Treasury Stock [Member]
Noncontrolling Interest [Line Items]
Balance				(593.7)
Net income				0.0
Other comprehensive income (loss)				0.0
Dividends declared				0.0
Dividends to non-controlling interest				0.0
Purchases of common shares				(2.6)
Issuance of shares pursuant to employee stock compensation plans				0.0
Income tax benefit arising from employee stock compensation plans				0.0
Stock based compensation				0.0
Balance		(596.3)		(596.3)
Non-controlling Interests [Member]
Noncontrolling Interest [Line Items]
Balance				27.2
Net income				2.9
Other comprehensive income (loss)				(0.7)
Dividends declared				0.0
Dividends to non-controlling interest				(1.5)
Purchases of common shares				0.0
Issuance of shares pursuant to employee stock compensation plans				0.0
Income tax benefit arising from employee stock compensation plans				0.0
Stock based compensation				0.0
Balance		$ 27.9		$ 27.9

[1] Condensed from audited financial statements

[2] Unaudited