Business Segments and Major Customers - Summary of Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total revenue	$ 199,549	$ 231,825
Segment profit (loss)	37,891	11,374
Service [Member]
Segment Reporting Information [Line Items]
Total revenue	165,012	150,678
Product [Member]
Segment Reporting Information [Line Items]
Total revenue	34,537	81,147
CA-NA [Member]
Segment Reporting Information [Line Items]
Total revenue	96,069	143,821
Segment profit (loss)	23,542	1,656
CA-NA [Member] | Service [Member]
Segment Reporting Information [Line Items]
Total revenue	92,027	88,783
CA-NA [Member] | Product [Member]
Segment Reporting Information [Line Items]
Total revenue	4,042	55,038
CA-ROW [Member]
Segment Reporting Information [Line Items]
Total revenue	32,931	19,169
Segment profit (loss)	(19,149)	(22,605)
CA-ROW [Member] | Service [Member]
Segment Reporting Information [Line Items]
Total revenue	19,772	14,245
CA-ROW [Member] | Product [Member]
Segment Reporting Information [Line Items]
Total revenue	13,159	4,924
BA [Member]
Segment Reporting Information [Line Items]
Total revenue	70,549	68,835
Segment profit (loss)	33,498	32,323
BA [Member] | Service [Member]
Segment Reporting Information [Line Items]
Total revenue	53,213	47,650
BA [Member] | Product [Member]
Segment Reporting Information [Line Items]
Total revenue	$ 17,336	$ 21,185