Stockholders Equity - Annual (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	May 19, 2015 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) class $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($)	Jun. 26, 2018 USD ($)	Dec. 14, 2017 USD ($)
Equity, Class of Stock [Line Items]
Common stock, shares authorized | shares		125,000,000
Preferred stock, shares authorized | shares		10,000,000	10,000,000
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.01	$ 0.01
Number of classes | class		2
Preferred stock dividends declared		$ 6,792	$ 6,792	$ 6,792
Convertible Preferred Stock, Shares Issued upon Conversion | shares	38.0619
Convertible Preferred Stock, Threshold Percentage of Stock Price Trigger		150.00%
Treasury Stock, Cost [Roll Forward]
Treasury stock, cost, beginning of period		$ 284,300
Shares purchased for minimum tax withholding under the Equity Plan or other similar transactions		15,147	15,217	12,310
Purchase of treasury stock, cost		47,300
Treasury stock, cost, end of period		346,900	$ 284,300
Treasury Stock, Average Cost Per Share [Roll Forward]
Embedded Derivative, No Longer Bifurcated, Amount Reclassified to Stockholders' Equity				28,974
Dividends, Cash		6,851
Convertible Debt
Treasury Stock, Average Cost Per Share [Roll Forward]
Embedded Derivative, No Longer Bifurcated, Amount Reclassified to Stockholders' Equity		29,645
Dividend Paid
Treasury Stock, Average Cost Per Share [Roll Forward]
Dividends, Cash		$ 5,700
Treasury Stock
Treasury Stock, Shares [Roll Forward]
Treasury stock, shares, beginning of period | shares		18,605,581
Shares purchased for minimum tax withholding under the Equity Plan or other similar transactions | shares		866,784
Treasury stock shares received, other | shares		7,747
Purchase of treasury stock, shares | shares		3,139,751
Treasury stock, shares, end of period | shares		22,619,863	18,605,581
Treasury Stock, Cost [Roll Forward]
Treasury stock, cost, beginning of period		$ 284,301
Shares purchased for minimum tax withholding under the Equity Plan or other similar transactions		15,147
Treasury stock received, value, other		108
Purchase of treasury stock, cost		47,314
Treasury stock, cost, end of period		$ 346,870	$ 284,301
Treasury Stock, Average Cost Per Share [Roll Forward]
Treasury stock, average cost per share, beginning of period, in dollars per share | $ / shares		$ 15.28
Shares purchased for minimum tax withholding under the Equity Plan or other similar transactions, Average Cost Per Share | $ / shares		17.48
Treasury stock received, per share, other | $ / shares		13.96
Purchase of treasury stock, average cost per share, in dollars per share | $ / shares		15.07
Treasury stock, average cost per share, end of period, in dollars per share | $ / shares		$ 15.33	$ 15.28
Additional Paid-in Capital | Convertible Debt
Treasury Stock, Average Cost Per Share [Roll Forward]
Embedded Derivative, No Longer Bifurcated, Amount Reclassified to Stockholders' Equity		$ 29,645
Convertible Preferred Stock
Equity, Class of Stock [Line Items]
Stock Issued During Period, Shares, Other | shares	120,750
Preferred Stock, Dividend Rate, Percentage	5.625%
Proceeds from Issuance of Preferred Stock, net of issuance costs	$ 117,200
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	$ 3,600
Preferred Stock, Liquidation Preference Per Share | $ / shares	$ 1,000
Convertible Preferred Stock, Shares Issued upon Conversion | shares		38.488
Convertible Preferred Stock | Retained Earnings/(Accumulated deficit)
Equity, Class of Stock [Line Items]
Preferred stock dividends declared		$ 6,792	$ 6,792	$ 6,792
Common Stock Class A
Equity, Class of Stock [Line Items]
Common stock, shares authorized | shares		62,500,000	62,500,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.01	$ 0.01
Treasury Stock, Shares [Roll Forward]
Treasury stock, shares, beginning of period | shares		18,605,581
Treasury stock, shares, end of period | shares		22,619,863	18,605,581
Treasury Stock, Cost [Roll Forward]
Treasury stock, cost, beginning of period		$ 284,301
Treasury stock, cost, end of period		346,870	$ 284,301
Common Stock Class A | Retained Earnings/(Accumulated deficit)
Treasury Stock, Average Cost Per Share [Roll Forward]
Dividends, Cash		$ 6,851
Common Stock Class B
Equity, Class of Stock [Line Items]
Common stock, shares authorized | shares		62,500,000	62,500,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.01	$ 0.01
Maximum
Equity, Class of Stock [Line Items]
Convertible Preferred Stock, Threshold Consecutive Trading Days		30 days
Minimum
Equity, Class of Stock [Line Items]
Convertible Preferred Stock, Threshold Consecutive Trading Days		20 days
Minimum | Call Option
Equity, Class of Stock [Line Items]
Option Indexed to Issuer's Equity, Strike Price | $ / shares		$ 26.27
Convertible Debt
Treasury Stock, Average Cost Per Share [Roll Forward]
Convertible debt, unamortized discount		$ 6,700	$ 14,900
Convertible Debt | 2022 convertible note
Treasury Stock, Average Cost Per Share [Roll Forward]
Convertible debt, unamortized discount						$ 23,400
Option Indexed to Issuer's Equity, Settlement Alternatives, Cash, at Fair Value					$ 29,000
Embedded Derivative, No Longer Bifurcated, Amount Reclassified to Stockholders' Equity		$ 29,600