Investment in Receivable Portfolios, Net - Summary of Changes in Balance of Investment in Receivable Portfolios (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Investment in Receivables Portfolio [Roll Forward]
Balance, beginning of period	$ 2,555,925	$ 2,469,593	$ 2,382,809	$ 2,440,669
Purchases of receivable portfolios	292,332	206,359	757,474	696,228
Transfer of portfolios				0
Disposals or transfers to held for sale	(3,801)		(11,269)
Gross collections	(442,996)	(406,961)	(1,330,041)	(1,288,866)
Put-backs and Recalls	(649)	(3,160)	(5,676)	(19,710)
Foreign currency adjustments	44,412	(27,534)	127,720	(127,570)
Revenue recognized	264,024	250,981	777,269	783,857
Portfolio allowance reversals, net	19,564	(91,447)	30,525	(86,777)
Balance, end of period	$ 2,728,811	$ 2,397,831	$ 2,728,811	$ 2,397,831
Revenue as a percentage of collections	59.60%	61.70%	58.40%	60.80%
Accrual Basis Portfolios
Investment in Receivables Portfolio [Roll Forward]
Balance, beginning of period	$ 2,541,590	$ 2,465,967	$ 2,368,366	$ 2,436,054
Purchases of receivable portfolios	292,332	206,359	756,305	696,228
Transfer of portfolios				(96)
Disposals or transfers to held for sale	(3,536)		(11,004)
Gross collections	(407,435)	(366,321)	(1,212,357)	(1,181,546)
Put-backs and Recalls	(407)	(3,103)	(5,401)	(19,680)
Foreign currency adjustments	44,366	(27,361)	127,852	(127,680)
Revenue recognized	230,403	212,664	665,818	683,752
Portfolio allowance reversals, net	17,817	(93,121)	25,551	(91,948)
Balance, end of period	$ 2,715,130	$ 2,395,084	$ 2,715,130	$ 2,395,084
Revenue as a percentage of collections	56.50%	58.10%	54.90%	57.90%
Cost Recovery Portfolios
Investment in Receivables Portfolio [Roll Forward]
Balance, beginning of period	$ 14,335	$ 3,626	$ 14,443	$ 4,615
Purchases of receivable portfolios	0	0	1,169	0
Transfer of portfolios				96
Disposals or transfers to held for sale	(265)		(265)
Gross collections	(435)	(706)	(1,534)	(2,063)
Put-backs and Recalls	0	0	0	(11)
Foreign currency adjustments	46	(173)	(132)	110
Revenue recognized	0	0	0	0
Portfolio allowance reversals, net	0	0	0	0
Balance, end of period	$ 13,681	$ 2,747	$ 13,681	$ 2,747
Revenue as a percentage of collections	0.00%	0.00%	0.00%	0.00%
Zero Basis Portfolios
Investment in Receivables Portfolio [Roll Forward]
Balance, beginning of period	$ 0	$ 0	$ 0	$ 0
Purchases of receivable portfolios	0	0	0	0
Transfer of portfolios				0
Disposals or transfers to held for sale	0		0
Gross collections	(35,126)	(39,934)	(116,150)	(105,257)
Put-backs and Recalls	(242)	(57)	(275)	(19)
Foreign currency adjustments	0	0	0	0
Revenue recognized	33,621	38,317	111,451	100,105
Portfolio allowance reversals, net	1,747	1,674	4,974	5,171
Balance, end of period	$ 0	$ 0	$ 0	$ 0
Revenue as a percentage of collections	95.70%	96.00%	96.00%	95.10%