Condensed consolidating guarantor financial information - Balance Sheets (Details) - USD ($) $ in Thousands	Jun. 26, 2016	Dec. 31, 2015	Jun. 28, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 476,490	$ 338,366	$ 325,010	$ 303,236
Accounts receivable, net	273,530	262,416
Accounts receivable from consolidated subsidiaries	0	0
Inventories, net	338,465	330,275
Prepaid expenses and other current assets	35,841	34,915
Prepaid taxes	30,369	30,895
Assets held for sale	7,026	6,972
Total current assets	1,161,721	1,003,839
Property, plant and equipment, net	314,665	316,123
Goodwill	1,301,348	1,295,852
Intangible assets, net	1,175,098	1,199,975
Investments in affiliates	244	152
Deferred tax assets	1,985	2,341
Notes receivable and other amounts due from consolidated subsidiaries	0	0
Other assets	45,146	53,492
Total assets	4,000,207	3,871,774
Current liabilities
Current borrowings	173,952	417,350
Accounts payable	72,787	66,305
Accounts payable to consolidated subsidiaries	0	0
Accrued expenses	63,396	64,017
Current portion of contingent consideration	7,453	7,291
Payroll and benefit-related liabilities	71,059	84,658
Accrued interest	5,688	7,480
Income taxes payable	12,957	8,059
Other current liabilities	16,512	8,960
Total current liabilities	423,804	664,120
Long-term borrowings	907,930	641,850
Deferred tax liabilities	317,327	315,983
Pension and other postretirement benefit liabilities	143,992	149,441
Noncurrent liability for uncertain tax positions	26,415	40,400
Notes payable and other amounts due to consolidated subsidiaries	0	0
Other liabilities	59,171	48,887
Total liabilities	1,878,639	1,860,681
Total common shareholders' equity	2,119,350	2,009,272
Noncontrolling interest	2,218	1,821
Total equity	2,121,568	2,011,093
Total liabilities and equity	4,000,207	3,871,774
Consolidation, Eliminations
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	3,885	4,386
Accounts receivable from consolidated subsidiaries	(2,677,363)	(2,707,052)
Inventories, net	(28,354)	(24,593)
Prepaid expenses and other current assets	3,665	3,665
Prepaid taxes	0	(413)
Assets held for sale	0	0
Total current assets	(2,698,167)	(2,724,007)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Investments in affiliates	(7,425,600)	(7,107,184)
Deferred tax assets	(91,136)	(97,133)
Notes receivable and other amounts due from consolidated subsidiaries	(3,139,816)	(3,016,538)
Other assets	0	0
Total assets	(13,354,719)	(12,944,862)
Current liabilities
Current borrowings	0	0
Accounts payable	0	0
Accounts payable to consolidated subsidiaries	(2,677,363)	(2,707,052)
Accrued expenses	0	0
Current portion of contingent consideration	0	0
Payroll and benefit-related liabilities	0	0
Accrued interest	0	0
Income taxes payable	(81)	(85)
Other current liabilities	0	0
Total current liabilities	(2,677,444)	(2,707,137)
Long-term borrowings	0	0
Deferred tax liabilities	(91,136)	(97,133)
Pension and other postretirement benefit liabilities	0	0
Noncurrent liability for uncertain tax positions	0	0
Notes payable and other amounts due to consolidated subsidiaries	(3,139,816)	(3,016,538)
Other liabilities	0	0
Total liabilities	(5,908,396)	(5,820,808)
Total common shareholders' equity	(7,446,323)	(7,124,054)
Noncontrolling interest	0	0
Total equity	(7,446,323)	(7,124,054)
Total liabilities and equity	(13,354,719)	(12,944,862)
Parent Company | Reportable Legal Entities
Current assets
Cash and cash equivalents	50,209	21,612	26,063	27,996
Accounts receivable, net	3,139	2,538
Accounts receivable from consolidated subsidiaries	4,914	5,276
Inventories, net	0	0
Prepaid expenses and other current assets	10,289	10,511
Prepaid taxes	8,579	16,686
Assets held for sale	2,901	2,901
Total current assets	80,031	59,524
Property, plant and equipment, net	2,771	2,931
Goodwill	0	0
Intangible assets, net	0	0
Investments in affiliates	5,913,792	5,724,226
Deferred tax assets	86,886	91,432
Notes receivable and other amounts due from consolidated subsidiaries	1,353,481	1,358,446
Other assets	22,443	22,602
Total assets	7,459,404	7,259,161
Current liabilities
Current borrowings	130,652	374,050
Accounts payable	3,802	1,945
Accounts payable to consolidated subsidiaries	2,423,041	2,478,109
Accrued expenses	14,963	15,399
Current portion of contingent consideration	0	0
Payroll and benefit-related liabilities	19,447	21,617
Accrued interest	5,670	7,455
Income taxes payable	0	0
Other current liabilities	4,777	1,300
Total current liabilities	2,602,352	2,899,875
Long-term borrowings	907,930	641,850
Deferred tax liabilities	0	0
Pension and other postretirement benefit liabilities	95,719	100,355
Noncurrent liability for uncertain tax positions	1,503	1,151
Notes payable and other amounts due to consolidated subsidiaries	1,709,543	1,585,727
Other liabilities	23,007	20,931
Total liabilities	5,340,054	5,249,889
Total common shareholders' equity	2,119,350	2,009,272
Noncontrolling interest	0	0
Total equity	2,119,350	2,009,272
Total liabilities and equity	7,459,404	7,259,161
Guarantor Subsidiaries | Reportable Legal Entities
Current assets
Cash and cash equivalents	1,089	0	298	0
Accounts receivable, net	4,832	4,326
Accounts receivable from consolidated subsidiaries	2,363,862	2,412,079
Inventories, net	203,774	205,163
Prepaid expenses and other current assets	5,993	4,702
Prepaid taxes	0	0
Assets held for sale	0	0
Total current assets	2,579,550	2,626,270
Property, plant and equipment, net	166,228	174,674
Goodwill	705,754	705,753
Intangible assets, net	724,239	762,084
Investments in affiliates	1,488,669	1,360,045
Deferred tax assets	0	0
Notes receivable and other amounts due from consolidated subsidiaries	1,786,335	1,658,092
Other assets	6,697	6,615
Total assets	7,457,472	7,293,533
Current liabilities
Current borrowings	0	0
Accounts payable	34,362	27,527
Accounts payable to consolidated subsidiaries	221,128	201,400
Accrued expenses	17,361	22,281
Current portion of contingent consideration	7,453	7,291
Payroll and benefit-related liabilities	17,637	29,305
Accrued interest	0	0
Income taxes payable	0	0
Other current liabilities	2,157	2,679
Total current liabilities	300,098	290,483
Long-term borrowings	0	0
Deferred tax liabilities	372,650	376,738
Pension and other postretirement benefit liabilities	32,004	32,274
Noncurrent liability for uncertain tax positions	17,825	17,722
Notes payable and other amounts due to consolidated subsidiaries	1,231,819	1,253,189
Other liabilities	23,505	15,685
Total liabilities	1,977,901	1,986,091
Total common shareholders' equity	5,479,571	5,307,442
Noncontrolling interest	0	0
Total equity	5,479,571	5,307,442
Total liabilities and equity	7,457,472	7,293,533
Non-Guarantor Subsidiaries | Reportable Legal Entities
Current assets
Cash and cash equivalents	425,192	316,754	$ 298,649	$ 275,240
Accounts receivable, net	261,674	251,166
Accounts receivable from consolidated subsidiaries	308,587	289,697
Inventories, net	163,045	149,705
Prepaid expenses and other current assets	15,894	16,037
Prepaid taxes	21,790	14,622
Assets held for sale	4,125	4,071
Total current assets	1,200,307	1,042,052
Property, plant and equipment, net	145,666	138,518
Goodwill	595,594	590,099
Intangible assets, net	450,859	437,891
Investments in affiliates	23,383	23,065
Deferred tax assets	6,235	8,042
Notes receivable and other amounts due from consolidated subsidiaries	0	0
Other assets	16,006	24,275
Total assets	2,438,050	2,263,942
Current liabilities
Current borrowings	43,300	43,300
Accounts payable	34,623	36,833
Accounts payable to consolidated subsidiaries	33,194	27,543
Accrued expenses	31,072	26,337
Current portion of contingent consideration	0	0
Payroll and benefit-related liabilities	33,975	33,736
Accrued interest	18	25
Income taxes payable	13,038	8,144
Other current liabilities	9,578	4,981
Total current liabilities	198,798	180,899
Long-term borrowings	0	0
Deferred tax liabilities	35,813	36,378
Pension and other postretirement benefit liabilities	16,269	16,812
Noncurrent liability for uncertain tax positions	7,087	21,527
Notes payable and other amounts due to consolidated subsidiaries	198,454	177,622
Other liabilities	12,659	12,271
Total liabilities	469,080	445,509
Total common shareholders' equity	1,966,752	1,816,612
Noncontrolling interest	2,218	1,821
Total equity	1,968,970	1,818,433
Total liabilities and equity	$ 2,438,050	$ 2,263,942