Revenue - Financial Statement Effect of Applying ASC 606 (Balance Sheet) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Receivables, net of allowances	$ 278,369	$ 262,845
Recoverable income taxes	7,673	7,921
Prepaid expenses	29,961	23,219
Other current assets	29,010	58,126
Accrued receivables, net	187,133
Deferred income taxes, net	22,109	66,749
Other noncurrent assets	56,826	36,483
Liabilities
Deferred revenue	111,639	107,543
Income taxes payable	6,178	9,898
Other current liabilities	64,312	102,904
Deferred income taxes, net	26,564	16,910
Stockholders' equity
Total stockholders' equity	979,022	$ 764,597
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Assets
Receivables, net of allowances	205,165
Recoverable income taxes	6,538
Prepaid expenses	30,702
Other current assets	28,795
Deferred income taxes, net	65,503
Other noncurrent assets	38,945
Liabilities
Deferred revenue	128,304
Income taxes payable	6,268
Other current liabilities	64,546
Deferred income taxes, net	7,876
Stockholders' equity
Total stockholders' equity	745,288
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Assets
Receivables, net of allowances	73,204
Recoverable income taxes	1,135
Prepaid expenses	(741)
Other current assets	215
Accrued receivables, net	187,133
Deferred income taxes, net	(43,394)
Other noncurrent assets	17,881
Liabilities
Deferred revenue	(16,665)
Income taxes payable	(90)
Other current liabilities	(234)
Deferred income taxes, net	18,688
Stockholders' equity
Total stockholders' equity	$ 233,734