Quarterly report pursuant to Section 13 or 15(d)

Income Taxes - Additional Information (Detail)

v3.8.0.1
Income Taxes - Additional Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Dec. 31, 2016
Schedule Of Income Taxes [Line Items]        
Effective tax rate 9.60% 14.00%    
U.S. federal and state statutory rate 25.00%      
Provisional tax $ 91,900   $ 99,900  
Reduction in provisional tax 8,000      
Cash and cash equivalents 700,071 $ 607,813 $ 736,431 $ 718,536
Non-US [Member]        
Schedule Of Income Taxes [Line Items]        
Cash and cash equivalents $ 297,400      
Non-US [Member] | Geographic concentration risk [Member] | Cash and Cash Equivalents Geographical Area [Member]        
Schedule Of Income Taxes [Line Items]        
Percentage of cash and cash equivalents 42.50%      
Non-US [Member] | Funds Available For Repatriation [Member]        
Schedule Of Income Taxes [Line Items]        
Cash and cash equivalents $ 124,900      
ASU 2016-09 [Member]        
Schedule Of Income Taxes [Line Items]        
Excess tax benefits recorded in earnings $ 1,100      
Minimum [Member]        
Schedule Of Income Taxes [Line Items]        
Effective tax rate 12.00%      
Minimum [Member] | Non-U.S jurisdictions [Member]        
Schedule Of Income Taxes [Line Items]        
Statutory federal rate 0.00%      
Maximum [Member]        
Schedule Of Income Taxes [Line Items]        
Effective tax rate 17.00%      
Maximum [Member] | Non-U.S jurisdictions [Member]        
Schedule Of Income Taxes [Line Items]        
Statutory federal rate 34.00%