Stockholders' Equity and Equity Compensation Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2014
Stockholders Equity And Equity Compensation Plans [Line Items]
Remaining number of shares available for repurchase	6,800,000		6,800,000
Repurchase of common stock for employee tax withholdings, shares			300,000	200,000
Repurchase of common stock for tax withholdings, value			$ 10,000	$ 5,900
Cash dividends declared per common share	$ 0.185	$ 0.175	$ 0.37	$ 0.35
Cash dividend	$ 6,000	$ 5,700	$ 12,000	$ 11,500
Stock warrants term					10 years
Stock warrants, exercise price					$ 26.68
Stock-based compensation expense	$ 5,600	$ 5,400	$ 12,086	$ 10,473
Performance Shares
Stockholders Equity And Equity Compensation Plans [Line Items]
Performance based awards granted to executive management shares			100,000
Vesting period			3 years
Restricted common stock
Stockholders Equity And Equity Compensation Plans [Line Items]
Vesting period	4 years		4 years
Migration Of Comcast Current Residential Customer Accounts
Stockholders Equity And Equity Compensation Plans [Line Items]
Number of stock warrants vesting			1,000,000
Comcast Corporation
Stockholders Equity And Equity Compensation Plans [Line Items]
Issuance of stock warrants					2,900,000
Client contract incentive related to stock warrants			$ 7,300
Amortization expense of client contract incentive related to stock warrants			$ 2,700
Stock warrants exercised			0
SEC Rule 10b5-1 Plan
Stockholders Equity And Equity Compensation Plans [Line Items]
Repurchase of common stock, shares			300,000	300,000
Total amount paid			$ 9,500	$ 7,000
Weighted-average price per share			$ 36.07	$ 27.06