Acquisitions - Fair Value of Assets Acquired and Liabilities Assumed (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 11, 2014	Mar. 31, 2014	Dec. 10, 2012	Jul. 27, 2012
Business Acquisition [Line Items]
Goodwill	$ 943,374	$ 773,048	$ 778,708
Prosoft Technology, Inc. [Member]
Business Acquisition [Line Items]
Cash				2,517
Receivables				5,559
Inventories				3,624
Other current assets				240
Property, plant and equipment				1,076
Goodwill				56,193
Intangible assets				40,800
Other non-current assets				622
Total assets				110,631
Accounts payable				2,851
Accrued liabilities				2,545
Other long-term / non-current liabilities				1,132
Total liabilities				6,528
Net assets				104,103
Grass Valley [Member]
Business Acquisition [Line Items]
Cash					9,441
Receivables					68,766
Inventories					19,984
Deferred taxes					1,355
Other current assets					4,172
Property, plant and equipment					22,661
Goodwill					119,589
Intangible assets					95,500
Other non-current assets					17,108
Total assets					358,576
Accounts payable					51,276
Accrued liabilities					57,374
Deferred revenue					14,000
Postretirement benefits					16,538
Other long-term / non-current liabilities					1,199
Total liabilities					140,387
Net assets					218,189
PPC Broadband, Inc. [Member]
Business Acquisition [Line Items]
Cash						6,874
Receivables						26,612
Inventories						45,465
Other current assets						868
Property, plant and equipment						26,856
Goodwill						277,091
Intangible assets						164,500
Other non-current assets						1,308
Total assets						549,574
Accounts payable						22,499
Accrued liabilities						4,104
Other long-term / non-current liabilities						579
Total liabilities						27,182
Net assets						522,392
Miranda Technologies Inc. [Member]
Business Acquisition [Line Items]
Cash							33,324
Receivables							27,592
Inventories							31,109
Other current assets							1,924
Property, plant and equipment							23,930
Goodwill							161,206
Intangible assets							159,991
Total assets							439,076
Accounts payable							23,917
Accrued liabilities							5,730
Current deferred tax liabilities							844
Other long-term / non-current liabilities							8,699
Non-current deferred tax liabilities							25,207
Total liabilities							64,397
Net assets							$ 374,679