Condensed consolidating guarantor financial information - Balance Sheets (Details) - USD ($) $ in Thousands	Apr. 02, 2017	Dec. 31, 2016	Mar. 27, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 689,129	$ 543,789	$ 392,558	$ 338,366
Accounts receivable, net	282,872	271,993
Accounts receivable from consolidated subsidiaries	0	0
Inventories, net	355,289	316,171
Prepaid expenses and other current assets	47,238	40,382
Prepaid taxes	20,599	8,179
Assets held for sale	0	2,879
Total current assets	1,395,127	1,183,393
Property, plant and equipment, net	355,234	302,899
Goodwill	1,815,498	1,276,720
Intangible assets, net	1,620,454	1,091,663
Deferred tax assets	1,963	1,712
Notes receivable and other amounts due from consolidated subsidiaries	0	0
Other assets	44,160	34,826
Total assets	5,232,436	3,891,213
Current liabilities
Current borrowings	131,095	183,071
Accounts payable	82,018	69,400
Accounts payable to consolidated subsidiaries	0	0
Accrued expenses	82,390	65,149
Current portion of contingent consideration	669	587
Payroll and benefit-related liabilities	65,927	82,679
Accrued interest	12,686	10,450
Income taxes payable	8,043	7,908
Other current liabilities	9,530	8,402
Total current liabilities	392,358	427,646
Long-term borrowings	1,957,797	850,252
Deferred tax liabilities	460,654	271,377
Pension and postretirement benefit liabilities	130,226	133,062
Noncurrent liability for uncertain tax positions	17,939	17,520
Notes payable and other amounts due to consolidated subsidiaries	0	0
Other liabilities	54,558	52,015
Total liabilities	3,013,532	1,751,872
Convertible notes - redeemable equity component	0	1,824
Mezzanine equity	0	1,824
Total shareholders' equity	2,218,904	2,137,517
Total liabilities and shareholders' equity	5,232,436	3,891,213
Reportable Legal Entities | Parent Company
Current assets
Cash and cash equivalents	153,100	14,571	23,992	21,612
Accounts receivable, net	2,215	2,551
Accounts receivable from consolidated subsidiaries	8,025	4,861
Inventories, net	0	0
Prepaid expenses and other current assets	14,084	14,239
Prepaid taxes	11,072	0
Assets held for sale		0
Total current assets	188,496	36,222
Property, plant and equipment, net	2,517	2,566
Goodwill	0	0
Intangible assets, net	0	0
Deferred tax assets	72,621	73,051
Notes receivable and other amounts due from consolidated subsidiaries	1,321,595	1,387,615
Other assets	7,203,940	6,044,337
Total assets	8,789,169	7,543,791
Current liabilities
Current borrowings	81,095	133,071
Accounts payable	4,335	4,540
Accounts payable to consolidated subsidiaries	2,290,413	2,242,814
Accrued expenses	19,473	16,827
Current portion of contingent consideration	0	0
Payroll and benefit-related liabilities	16,858	20,610
Accrued interest	12,657	10,429
Income taxes payable	0	1,246
Other current liabilities	1,926	2,262
Total current liabilities	2,426,757	2,431,799
Long-term borrowings	1,957,797	850,252
Deferred tax liabilities	0	0
Pension and postretirement benefit liabilities	82,623	85,645
Noncurrent liability for uncertain tax positions	1,432	1,169
Notes payable and other amounts due to consolidated subsidiaries	2,076,792	2,011,737
Other liabilities	24,864	23,848
Total liabilities	6,570,265	5,404,450
Convertible notes - redeemable equity component		1,824
Mezzanine equity		1,824
Total shareholders' equity	2,218,904	2,137,517
Total liabilities and shareholders' equity	8,789,169	7,543,791
Reportable Legal Entities | Guarantor Subsidiaries
Current assets
Cash and cash equivalents	7,593	1,031	1,005	0
Accounts receivable, net	34,464	8,768
Accounts receivable from consolidated subsidiaries	2,238,256	2,176,059
Inventories, net	222,619	200,852
Prepaid expenses and other current assets	9,477	5,332
Prepaid taxes	0	0
Assets held for sale		0
Total current assets	2,512,409	2,392,042
Property, plant and equipment, net	207,818	163,847
Goodwill	1,228,353	708,546
Intangible assets, net	1,167,974	640,999
Deferred tax assets	0	0
Notes receivable and other amounts due from consolidated subsidiaries	2,151,605	2,085,538
Other assets	1,578,527	1,525,285
Total assets	8,846,686	7,516,257
Current liabilities
Current borrowings	0	0
Accounts payable	40,095	30,924
Accounts payable to consolidated subsidiaries	255,530	214,203
Accrued expenses	26,116	18,126
Current portion of contingent consideration	669	587
Payroll and benefit-related liabilities	15,707	26,672
Accrued interest	0	0
Income taxes payable	0	0
Other current liabilities	4,153	3,643
Total current liabilities	342,270	294,155
Long-term borrowings	0	0
Deferred tax liabilities	504,454	316,526
Pension and postretirement benefit liabilities	31,223	31,561
Noncurrent liability for uncertain tax positions	13,731	13,684
Notes payable and other amounts due to consolidated subsidiaries	1,203,358	1,264,004
Other liabilities	15,770	15,695
Total liabilities	2,110,806	1,935,625
Convertible notes - redeemable equity component		0
Mezzanine equity		0
Total shareholders' equity	6,735,880	5,580,632
Total liabilities and shareholders' equity	8,846,686	7,516,257
Reportable Legal Entities | Non-Guarantor Subsidiaries
Current assets
Cash and cash equivalents	528,436	528,187	$ 367,561	$ 316,754
Accounts receivable, net	241,897	255,815
Accounts receivable from consolidated subsidiaries	338,230	309,149
Inventories, net	158,358	140,406
Prepaid expenses and other current assets	20,340	17,474
Prepaid taxes	9,527	7,766
Assets held for sale		2,879
Total current assets	1,296,788	1,261,676
Property, plant and equipment, net	144,899	136,486
Goodwill	587,145	568,174
Intangible assets, net	452,480	450,664
Deferred tax assets	5,434	5,185
Notes receivable and other amounts due from consolidated subsidiaries	0	0
Other assets	30,859	29,962
Total assets	2,517,605	2,452,147
Current liabilities
Current borrowings	50,000	50,000
Accounts payable	37,588	33,936
Accounts payable to consolidated subsidiaries	38,568	33,052
Accrued expenses	36,801	30,196
Current portion of contingent consideration	0	0
Payroll and benefit-related liabilities	33,362	35,397
Accrued interest	29	21
Income taxes payable	7,519	6,577
Other current liabilities	3,451	2,497
Total current liabilities	207,318	191,676
Long-term borrowings	0	0
Deferred tax liabilities	32,292	31,375
Pension and postretirement benefit liabilities	16,380	15,856
Noncurrent liability for uncertain tax positions	2,776	2,667
Notes payable and other amounts due to consolidated subsidiaries	193,050	197,412
Other liabilities	13,924	12,472
Total liabilities	465,740	451,458
Convertible notes - redeemable equity component		0
Mezzanine equity		0
Total shareholders' equity	2,051,865	2,000,689
Total liabilities and shareholders' equity	2,517,605	2,452,147
Eliminations
Current assets
Cash and cash equivalents	0	0
Accounts receivable, net	4,296	4,859
Accounts receivable from consolidated subsidiaries	(2,584,511)	(2,490,069)
Inventories, net	(25,688)	(25,087)
Prepaid expenses and other current assets	3,337	3,337
Prepaid taxes	0	413
Assets held for sale		0
Total current assets	(2,602,566)	(2,506,547)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Deferred tax assets	(76,092)	(76,524)
Notes receivable and other amounts due from consolidated subsidiaries	(3,473,200)	(3,473,153)
Other assets	(8,769,166)	(7,564,758)
Total assets	(14,921,024)	(13,620,982)
Current liabilities
Current borrowings	0	0
Accounts payable	0	0
Accounts payable to consolidated subsidiaries	(2,584,511)	(2,490,069)
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	524	85
Other current liabilities	0	0
Total current liabilities	(2,583,987)	(2,489,984)
Long-term borrowings	0	0
Deferred tax liabilities	(76,092)	(76,524)
Pension and postretirement benefit liabilities	0	0
Noncurrent liability for uncertain tax positions	0	0
Notes payable and other amounts due to consolidated subsidiaries	(3,473,200)	(3,473,153)
Other liabilities	0	0
Total liabilities	(6,133,279)	(6,039,661)
Convertible notes - redeemable equity component		0
Mezzanine equity		0
Total shareholders' equity	(8,787,745)	(7,581,321)
Total liabilities and shareholders' equity	$ (14,921,024)	$ (13,620,982)