Condensed consolidating guarantor financial information - Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 333,558	$ 543,789	$ 338,366	$ 303,236
Accounts receivable, net	345,875	271,993
Accounts receivable from consolidated subsidiaries	0	0
Inventories, net	395,744	316,171
Prepaid expenses and other current assets	47,882	40,382
Prepaid taxes	5,748	8,179
Assets held for sale	0	2,879
Total current assets	1,128,807	1,183,393
Property, plant and equipment, net	382,999	302,899	316,123
Goodwill	2,235,592	1,276,720	1,295,852
Intangibles assets, net	2,383,748	1,091,663
Investments in affiliates	0	0
Deferred tax assets	3,810	1,712
Notes receivable and other amounts due from consolidated subsidiaries	0	0
Other assets	46,536	34,826
Total assets	6,181,492	3,891,213
Current liabilities
Current borrowings	86,625	183,071
Accounts payable	92,027	69,400
Accounts payable to consolidated subsidiaries	0	0
Accrued expenses	96,853	65,149
Current portion of contingent consideration	74,224	587
Payroll and benefit-related liabilities	107,415	82,679
Accrued interest	6,165	10,450
Income taxes payable	11,514	7,908
Other current liabilities	9,053	8,402
Total current liabilities	483,876	427,646
Long-term borrowings	2,162,927	850,252
Deferred tax liabilities	603,676	271,377
Pension and postretirement benefit liabilities	121,410	133,062
Noncurrent liability for uncertain tax positions	12,296	17,520
Notes payable and other amounts due to consolidated subsidiaries	0	0
Noncurrent contingent consideration	197,912	6,516
Other liabilities	168,864	45,499
Total liabilities	3,750,961	1,751,872
Convertible notes - redeemable equity component	0	1,824
Mezzanine equity	0	1,824
Total shareholders' equity	2,430,531	2,137,517	2,011,093	1,913,699
Total liabilities and shareholders' equity	6,181,492	3,891,213
Eliminations
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	4,663	4,859
Accounts receivable from consolidated subsidiaries	(2,633,841)	(2,490,069)
Inventories, net	(26,279)	(25,087)
Prepaid expenses and other current assets	3,982	3,337
Prepaid taxes	0	413
Assets held for sale		0
Total current assets	(2,651,475)	(2,506,547)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangibles assets, net	0	0
Investments in affiliates	(8,896,872)	(7,564,758)
Deferred tax assets	(2,261)	(76,524)
Notes receivable and other amounts due from consolidated subsidiaries	(4,386,004)	(3,473,153)
Other assets	0	0
Total assets	(15,936,612)	(13,620,982)
Current liabilities
Current borrowings	0	0
Accounts payable	0	0
Accounts payable to consolidated subsidiaries	(2,633,841)	(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	0	85
Other current liabilities	0	0
Total current liabilities	(2,633,841)	(2,489,984)
Long-term borrowings	0	0
Deferred tax liabilities	(2,261)	(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	(4,386,004)	(3,473,153)
Noncurrent contingent consideration	0	0
Other liabilities	0	0
Total liabilities	(7,022,106)	(6,039,661)
Convertible notes - redeemable equity component		0
Mezzanine equity		0
Total shareholders' equity	(8,914,506)	(7,581,321)
Total liabilities and shareholders' equity	(15,936,612)	(13,620,982)
Parent Company
Current assets
Cash and cash equivalents	37,803	14,571	21,612	27,996
Accounts receivable, net	2,414	2,551
Accounts receivable from consolidated subsidiaries	14,478	4,861
Inventories, net	0	0
Prepaid expenses and other current assets	14,874	14,239
Prepaid taxes	0	0
Assets held for sale		0
Total current assets	69,569	36,222
Property, plant and equipment, net	2,088	2,566
Goodwill	0	0
Intangibles assets, net	0	0
Investments in affiliates	7,203,175	6,022,042
Deferred tax assets	0	73,051
Notes receivable and other amounts due from consolidated subsidiaries	2,154,172	1,387,615
Other assets	31,173	22,295
Total assets	9,460,177	7,543,791
Current liabilities
Current borrowings	36,625	133,071
Accounts payable	4,269	4,540
Accounts payable to consolidated subsidiaries	2,310,570	2,242,814
Accrued expenses	17,957	16,827
Current portion of contingent consideration	0	0
Payroll and benefit-related liabilities	21,145	20,610
Accrued interest	6,133	10,429
Income taxes payable	4,352	1,246
Other current liabilities	1,461	2,262
Total current liabilities	2,402,512	2,431,799
Long-term borrowings	2,162,927	850,252
Deferred tax liabilities	88,512	0
Pension and postretirement benefit liabilities	70,860	85,645
Noncurrent liability for uncertain tax positions	1,117	1,169
Notes payable and other amounts due to consolidated subsidiaries	2,155,146	2,011,737
Noncurrent contingent consideration	0	0
Other liabilities	148,572	23,848
Total liabilities	7,029,646	5,404,450
Convertible notes - redeemable equity component		1,824
Mezzanine equity		1,824
Total shareholders' equity	2,430,531	2,137,517
Total liabilities and shareholders' equity	9,460,177	7,543,791
Guarantor Subsidiaries
Current assets
Cash and cash equivalents	8,933	1,031	0	0
Accounts receivable, net	57,818	8,768
Accounts receivable from consolidated subsidiaries	2,276,248	2,176,059
Inventories, net	245,533	200,852
Prepaid expenses and other current assets	9,236	5,332
Prepaid taxes	0	0
Assets held for sale		0
Total current assets	2,597,768	2,392,042
Property, plant and equipment, net	213,663	163,847
Goodwill	1,246,144	708,546
Intangibles assets, net	1,355,275	640,999
Investments in affiliates	1,674,077	1,519,031
Deferred tax assets	0	0
Notes receivable and other amounts due from consolidated subsidiaries	2,231,832	2,085,538
Other assets	6,397	6,254
Total assets	9,325,156	7,516,257
Current liabilities
Current borrowings	0	0
Accounts payable	46,992	30,924
Accounts payable to consolidated subsidiaries	261,121	214,203
Accrued expenses	31,827	18,126
Current portion of contingent consideration	74,224	587
Payroll and benefit-related liabilities	44,009	26,672
Accrued interest	0	0
Income taxes payable	0	0
Other current liabilities	3,775	3,643
Total current liabilities	461,948	294,155
Long-term borrowings	0	0
Deferred tax liabilities	265,426	316,526
Pension and postretirement benefit liabilities	32,750	31,561
Noncurrent liability for uncertain tax positions	8,196	13,684
Notes payable and other amounts due to consolidated subsidiaries	2,022,682	1,264,004
Noncurrent contingent consideration	186,923	6,516
Other liabilities	7,850	9,179
Total liabilities	2,985,775	1,935,625
Convertible notes - redeemable equity component		0
Mezzanine equity		0
Total shareholders' equity	6,339,381	5,580,632
Total liabilities and shareholders' equity	9,325,156	7,516,257
Non-Guarantor Subsidiaries
Current assets
Cash and cash equivalents	286,822	528,187	$ 316,754	$ 275,240
Accounts receivable, net	280,980	255,815
Accounts receivable from consolidated subsidiaries	343,115	309,149
Inventories, net	176,490	140,406
Prepaid expenses and other current assets	19,790	17,474
Prepaid taxes	5,748	7,766
Assets held for sale		2,879
Total current assets	1,112,945	1,261,676
Property, plant and equipment, net	167,248	136,486
Goodwill	989,448	568,174
Intangibles assets, net	1,028,473	450,664
Investments in affiliates	19,620	23,685
Deferred tax assets	6,071	5,185
Notes receivable and other amounts due from consolidated subsidiaries	0	0
Other assets	8,966	6,277
Total assets	3,332,771	2,452,147
Current liabilities
Current borrowings	50,000	50,000
Accounts payable	40,766	33,936
Accounts payable to consolidated subsidiaries	62,150	33,052
Accrued expenses	47,069	30,196
Current portion of contingent consideration	0	0
Payroll and benefit-related liabilities	42,261	35,397
Accrued interest	32	21
Income taxes payable	7,162	6,577
Other current liabilities	3,817	2,497
Total current liabilities	253,257	191,676
Long-term borrowings	0	0
Deferred tax liabilities	251,999	31,375
Pension and postretirement benefit liabilities	17,800	15,856
Noncurrent liability for uncertain tax positions	2,983	2,667
Notes payable and other amounts due to consolidated subsidiaries	208,176	197,412
Noncurrent contingent consideration	10,989	0
Other liabilities	12,442	12,472
Total liabilities	757,646	451,458
Convertible notes - redeemable equity component		0
Mezzanine equity		0
Total shareholders' equity	2,575,125	2,000,689
Total liabilities and shareholders' equity	$ 3,332,771	$ 2,452,147