Acquisitions - Summary of Estimated Fair Values Allocated to Major Classes of Assets Acquired and Liabilities Assumed (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Cable Holdings [Member] | Assets Acquired [Member]
Business Acquisition [Line Items]
Accounts receivable and other current assets	$ 1,110
Furniture and equipment	480
Identifiable intangible assets	2,390
Goodwill	3,958
Cable Holdings [Member] | Liabilities Assumed [Member]
Business Acquisition [Line Items]
Accounts receivable and other current assets
Furniture and equipment
Identifiable intangible assets
Goodwill
Accounts payable and other liabilities	788
Ascolta [Member] | Assets Acquired [Member]
Business Acquisition [Line Items]
Accounts receivable and other current assets	849
Furniture and equipment	370
Identifiable intangible assets	1,670
Goodwill	3,332
Ascolta [Member] | Liabilities Assumed [Member]
Business Acquisition [Line Items]
Other current liabilities	$ 1,035