Fair Value Measurements - Financial Instruments Not Required to be Carried at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Carrying Amount
Financial Assets
Investment in receivable portfolios, net	$ 3,225,678	$ 3,291,918
Carrying Amount | Convertible notes and exchangeable notes
Financial Liabilities
Convertible Notes and Exchangeable Notes	422,500	564,136
Carrying Amount | Secured Debt
Financial Liabilities
Senior Secured Notes	1,613,557	1,642,058
Estimated Fair Value
Financial Assets
Investment in receivable portfolios, net	3,615,300	3,705,672
Estimated Fair Value | Convertible notes and exchangeable notes
Financial Liabilities
Convertible Notes and Exchangeable Notes	481,126	622,081
Estimated Fair Value | Secured Debt
Financial Liabilities
Senior Secured Notes	$ 1,683,277	$ 1,684,729