Reconciliation of Total Segment Profit to Operating Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment profit	$ 371,545	$ 279,554	$ 249,865
Amortization of intangibles	44,023	44,263	47,349
Unallocated general and administrative expenses	85,705	79,755	84,448
Operating income	241,817	155,536	118,068
Interest expense	32,343	36,846	38,667
Interest income	715	318	429
Other expense (income), net	25,458	(991)	(12,355)
Income before income tax expense and equity in net loss of affiliate	$ 184,731	$ 119,999	$ 92,185