Investment in Receivable Portfolios, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
(Reversal of) provision for allowances on receivable portfolios, net	$ (41,473)	$ (41,236)	$ 84,177
Reduction in allowance charges	55,894	53,283	9,834
Allowance charges	14,421	12,047	94,011
Face value of receivable portfolios	8,500,000	10,100,000
Purchase price of receivable portfolios	$ 1,131,898	$ 1,058,235	906,719
Purchase cost as a percentage of face value	13.30%	10.50%
Estimated future collections at acquisition for receivable portfolios	$ 2,300,000	$ 2,200,000
Zero basis revenue	125,200	144,100	$ 138,100
Accretable Yield
Accounts, Notes, Loans and Financing Receivable [Line Items]
(Reversal of) provision for allowances on receivable portfolios, net	(32,429)	(34,294)
Estimate of Zero Basis Cash Flows
Accounts, Notes, Loans and Financing Receivable [Line Items]
(Reversal of) provision for allowances on receivable portfolios, net	$ (9,044)	$ (6,942)