Employee plans - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($) Employee shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of unissued common stock available for grant under the plans (in shares) | shares	3,800,000	3,800,000
Age requirement for vesting provision, minimum		55 years
Completion of service period (in years) for stock awards		5 years
Option vesting period (in years)		3 years
Share-based compensation expense		$ 9,500,000	$ 9,400,000	$ 10,400,000
Proceeds from exercise of stock options		0	3,700,000	3,400,000
Deferred compensation Liability	$ 12,300,000	$ 12,300,000	12,600,000
Number of former associates | Employee	5,800
Lump sum payments made to former associates	$ 215,900,000
Pension Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Matching contribution by the company as percentage of participants' contribution		50.00%
Percentage of eligible pay contributed by participants that will be matched		6.00%
Cost recognized for contribution plans		$ 10,700,000	9,900,000	10,600,000
International Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cost recognized for contribution plans		19,000,000	21,400,000	25,200,000
Pension Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected pretax amortization of net loss in 2017		174,100,000
Expected pretax amortization of prior service cost (credit) in 2017		(5,100,000)
Recognized net actuarial loss		156,300,000
Amortization of prior service credit		(5,500,000)
Estimated cash contributions by the company in 2017		127,700,000
International Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized net actuarial loss		40,300,000	63,600,000	40,200,000
Amortization of prior service credit		(3,000,000)	(1,900,000)	(2,100,000)
Estimated cash contributions by the company in 2017		73,300,000
Plan assets measured using NAV as a practical expedient	1,434,200,000	1,434,200,000	1,631,300,000
U.S. Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized net actuarial loss		116,000,000	132,700,000	109,700,000
Amortization of prior service credit		(2,500,000)	(2,400,000)	(400,000)
Estimated cash contributions by the company in 2017		54,400,000
Plan assets measured using NAV as a practical expedient	164,800,000	164,800,000	150,500,000
Other Postretirement Benefit Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected pretax amortization of net loss in 2017		1,200,000
Expected pretax amortization of prior service cost (credit) in 2017		(400,000)
Recognized net actuarial loss		500,000	1,800,000	1,700,000
Amortization of prior service credit		0	1,100,000	1,700,000
Estimated cash contributions by the company in 2017		13,000,000
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense		7,500,000	4,700,000	3,300,000
Total unrecognized compensation cost	8,200,000	$ 8,200,000
Unrecognized compensation cost, Weighted-average recognition period		2 years
Aggregate weighted-average grant-date fair value of units granted		$ 12,900,000	10,200,000	12,800,000
Aggregate weighted-average grant-date fair value of units vested		3,500,000	2,100,000	3,300,000
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense		2,000,000	4,700,000	7,100,000
Total intrinsic value of options exercised		0	$ 600,000	$ 4,700,000
Total unrecognized compensation cost	$ 1,400,000	$ 1,400,000
Unrecognized compensation cost, Weighted-average recognition period		1 year 2 months 12 days
Performance-Based Unit | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares which will vest after achievement of goals (in shares) | shares		0
Performance-Based Unit | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares which will vest after achievement of goals (in shares) | shares		2.0
Options Issued in 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum contractual term of options granted (in years)		7 years
Options Issued Before 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum contractual term of options granted (in years)		5 years