Purchases of ARRIS Shares (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Jun. 30, 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased		1,700,000	3,300,000	6,400,000
Average Price Paid Per Share		$ 26.20	$ 25.44	$ 23.47
Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plans or Programs		$ 295,000			$ 295,000
April 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased	[1]				1,500,747
Average Price Paid Per Share					$ 25.89
Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plans or Programs		300,000			$ 300,000
May 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased	[1]				4,428
Average Price Paid Per Share					$ 28.01
Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plans or Programs		300,000			$ 300,000
June 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased	[1]				172,980
Average Price Paid Per Share					$ 28.93
Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plans or Programs		$ 295,000			$ 295,000
Shares Purchased as Part of Publicly Announced Plans of Programs | April 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased					1,500,747
Shares Purchased as Part of Publicly Announced Plans of Programs | June 2017
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased					172,841

[1] 4,567 shares were subject to equity awards that were cancelled for cash to satisfy minimum tax withholding obligations that arose on the vesting of shares of restricted stock units.