Schedule of Change in Projected Benefit Obligations, Fair Value of Plan Assets and the Funded Status of Pension Plan (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Change in Plan Assets:
Fair value of plan assets at beginning of year		$ 18,510
Fair value of plan assets at end of year				$ 18,510
U.S. Pension Plans
Change in Projected Benefit Obligation:
Projected benefit obligation at beginning of year		45,270		42,999
Interest cost		1,733		1,751		$ 1,716
Actuarial loss		3,868		2,024
Benefit payments		(1,651)		(1,504)
Projected benefit obligation at end of year		49,220		45,270		42,999
Change in Plan Assets:
Fair value of plan assets at beginning of year		18,510	[1]	13,516
Actual return on plan assets		949		751
Company contributions		1,856		5,747
Expenses and benefits paid from plan assets		(1,651)		(1,504)
Fair value of plan assets at end of year		19,664	[1]	18,510	[1]	13,516
Funded Status:
Funded status of plan		(29,557)		(26,760)
Unrecognized actuarial loss (gain)	[2]	13,981		10,720
Net amount recognized		(15,576)		(16,040)
Non-U.S. Pension Plans
Change in Projected Benefit Obligation:
Projected benefit obligation at beginning of year		35,706		36,372
Service cost		664		703		738
Interest cost		486		614		661
Actuarial loss		121		81
Benefit payments				(1,041)
Settlements		(1,596)		(1,626)
Foreign currency		2,755		603
Projected benefit obligation at end of year		38,136		35,706		36,372
Change in Plan Assets:
Fair value of plan assets at beginning of year		19,011	[1]	9,232
Actual return on plan assets		183		131
Company contributions		1,259		11,120
Settlements		(1,596)		(1,626)
Foreign currency		1,467		154
Fair value of plan assets at end of year		20,324	[1]	19,011	[1]	$ 9,232
Funded Status:
Funded status of plan		(17,812)		(16,695)
Unrecognized actuarial loss (gain)	[2]	(1,857)		(2,038)
Net amount recognized		$ (19,669)		$ (18,733)

[1] In addition to the U.S. pension plan assets, ARRIS has established two rabbi trusts to further fund the pension obligations of the Executive Chairman and certain executive officers of $25.4 million as of December 31, 2017 and $21.2 million as of December 31, 2016, and are included in Investments on the Consolidated Balance Sheets.

[2] The accumulated other comprehensive income on the Consolidated Balance Sheets as of December 31, 2017 and 2016 is presented net of income tax.