Stockholders' Equity and Equity Compensation Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Mar. 31, 2017	Jan. 31, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2014
Stockholders Equity And Equity Compensation Plans [Line Items]
Remaining number of shares available for repurchase	6,600,000		6,600,000
Repurchase of common stock for employee tax withholdings, shares			200,000	200,000
Repurchase of common stock for tax withholdings, value			$ 6,100	$ 9,500
Cash dividends declared per common share			$ 0.1975	$ 0.185
Cash dividend			$ 6,700	$ 6,000
Stock warrants term						10 years
Stock warrants, exercise price						$ 26.68
Number of stock warrants vested					1,400,000
Stock warrants outstanding	1,500,000		1,500,000
Remaining number of stock warrants vested			0
Carrying amount of common stock warrants					$ 16,007
Stock-based compensation expense			$ 5,670	$ 6,506
Performance Shares
Stockholders Equity And Equity Compensation Plans [Line Items]
Performance based awards granted to executive management and certain key employees shares			100,000
Vesting period			3 years
Restricted common stock
Stockholders Equity And Equity Compensation Plans [Line Items]
Vesting period			4 years
Senior Subordinated Convertible Notes 2010
Stockholders Equity And Equity Compensation Plans [Line Items]
Common shares from treasury stock delivered to settle conversion obligation in excess of par value	694,240
Carrying value of shares of treasury stock delivered	$ 16,500		$ 16,500
Carrying value of treasury stock delivered, per share	$ 23.71
Conversion obligation in excess of par value	$ 28,800
Common stock Warrants
Stockholders Equity And Equity Compensation Plans [Line Items]
Stock warrants exercised		1,400,000
Common shares from treasury stock delivered to settle conversion obligation in excess of par value		649,221
Fair value of shares of treasury stock delivered		$ 31,500
Carrying value of shares of treasury stock delivered		$ 15,400
Carrying value of treasury stock delivered, per share		$ 23.66
Carrying amount of common stock warrants		$ 16,000
Comcast Corporation
Stockholders Equity And Equity Compensation Plans [Line Items]
Issuance of stock warrants						2,900,000
Stock warrants exercised		1,400,000
Comcast Corporation | Stock Warrants
Stockholders Equity And Equity Compensation Plans [Line Items]
Client contract incentive related to stock warrants			16,000
Amortization expense of client contract incentive related to stock warrants			$ 5,500
SEC Rule 10b5-1 Plan
Stockholders Equity And Equity Compensation Plans [Line Items]
Repurchase of common stock, shares			100,000	300,000
Total amount paid			$ 5,400	$ 9,500
Weighted-average price per share			$ 42.85	$ 36.07