Total Revenues Gross Profit and Long Lived Assets Excluding Long Term Deferred Tax Assets (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets
Total revenues									$ 486,327	$ 497,638	$ 503,843
Gross profit	$ 108,895	$ 95,878	$ 92,387	$ 89,193	$ 106,032	$ 98,763	$ 95,562	$ 97,782	386,353	398,139	407,194
Long-lived assets	143,716				60,053				143,716	60,053
Domestic
Revenues from External Customers and Long-Lived Assets
Total revenues									273,581	287,258	293,251
Gross profit									216,365	228,310	234,266
Long-lived assets	118,168				49,611				118,168	49,611
EMEA
Revenues from External Customers and Long-Lived Assets
Total revenues									159,643	156,706	154,716
Gross profit									126,939	126,315	126,296
Long-lived assets	13,636				5,931				13,636	5,931
Other Regions
Revenues from External Customers and Long-Lived Assets
Total revenues									53,103	53,674	55,876
Gross profit									43,049	43,514	$ 46,632
Long-lived assets	$ 11,912				$ 4,511				$ 11,912	$ 4,511