Revenue by Geographic Area (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 1,095,250	$ 988,465	$ 942,753
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	417,342	367,937	354,433
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	126,262	120,160	104,299
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	108,216	99,814	94,546
South Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	63,011	56,790	55,142
France
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	53,672	49,294	49,444
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	13,824	13,284	13,314
Other European
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	153,826	139,813	145,985
Other international
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 159,097	$ 141,373	$ 125,590