Non-controlling interests (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014
Noncontrolling Interest [Line Items]
Balance	[1]			$ 888.9
Net income		$ 30.3	$ 37.8	93.9	$ 73.5
Other comprehensive income (loss)		(34.2)	$ (26.9)	(61.5)	$ (19.5)
Dividends declared				(5.4)
Dividends to non-controlling interest				(0.9)
Issuance of shares pursuant to employee stock compensation plans				1.3
Income tax benefit arising from employee stock compensation plans				0.8
Stock based compensation				7.6
Balance	[2]	924.7		924.7
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
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				373.0
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				1.3
Income tax benefit arising from employee stock compensation plans				0.8
Stock based compensation				7.6
Balance		382.7		382.7
Retained Earnings [Member]
Noncontrolling Interest [Line Items]
Balance				1,191.8
Net income				91.0
Other comprehensive income (loss)				0.0
Dividends declared				(5.4)
Dividends to non-controlling interest				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		1,277.4		1,277.4
Accumulated Other Comprehensive Income (Loss) [Member]
Noncontrolling Interest [Line Items]
Balance				(112.9)
Net income				0.0
Other comprehensive income (loss)				(60.4)
Dividends declared				0.0
Dividends to non-controlling interest				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		(173.3)		(173.3)
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
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		(593.7)		(593.7)
Noncontrolling Interests [Member]
Noncontrolling Interest [Line Items]
Balance				25.9
Net income				2.9
Other comprehensive income (loss)				(1.1)
Dividends declared				0.0
Dividends to non-controlling interest				(0.9)
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		$ 26.8		$ 26.8

[1] Condensed from audited financial statements

[2] Unaudited