Stockholders' Equity and Equity Compensation Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended			6 Months Ended		12 Months Ended
	May 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2014	Apr. 30, 2020
Stockholders Equity And Equity Compensation Plans [Line Items]
Remaining number of shares available for repurchase		4,800,000			4,800,000
Repurchase of common stock for employee tax withholdings, shares		2,000		4,000	159,000	107,000
Repurchase of common stock for tax withholdings, value		$ 100		$ 400	$ 7,700	$ 4,500
Cash dividends declared per common share		$ 0.235		$ 0.2225
Cash dividend		$ 7,800		$ 7,400	15,500	14,700
Stock warrants term							10 years
Stock warrants, exercise price							$ 26.68
Stock-based compensation expense		$ 5,200		$ 4,800	$ 10,112	$ 8,500
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 maturity date					first quarter of 2022
Vesting period			2 years
Restricted common stock
Stockholders Equity And Equity Compensation Plans [Line Items]
Vesting period					4 years
Comcast
Stockholders Equity And Equity Compensation Plans [Line Items]
Issuance of stock warrants							2,900,000
Stock warrants issued		1,000,000.0			1,000,000.0
Stock warrants vested					0
Stock Incentive Plan 2005
Stockholders Equity And Equity Compensation Plans [Line Items]
Increase in number of shares approved for issuance under incentive plan	3,600,000
Number of shares approved for issuance under incentive plan	25,000,000.0							21,400,000
SEC Rule 10b5-1 Plan
Stockholders Equity And Equity Compensation Plans [Line Items]
Repurchase of common stock, shares		9,000		144,000	151,000	393,000
Total amount paid		$ 400		$ 6,500	$ 6,800	$ 15,800
Weighted-average price per share		$ 40.74		$ 45.39	$ 44.99	$ 40.31