Reconciliation of Net Income to Adjusted Segment Earnings before Interest, Taxes, Depreciation and Amortization (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting [Abstract]
Net income		$ 32,214	$ 21,691	$ 41,074	$ 78,419
Income tax provision		9,197	10,292	17,601	44,115
Interest income and other		(1,103)	(3,213)	(3,300)	(9,895)
Interest expense		6,760	6,304	18,811	18,836
Unallocated corporate expenses	[1]	18,827	21,738	60,166	60,890
Segment depreciation expense		6,603	7,920	20,602	22,128
Amortization of intangible assets		2,882	2,845	7,797	8,041
Segment special charges				26,830	6,811
Remeasurement of acquisition-related contingent consideration				702	980
Total Adjusted Segment EBITDA		$ 75,380	$ 67,577	$ 190,283	$ 230,325

[1] Includes $3.2 million special charges for corporate for the nine months ended September 30, 2017.