Segment Information - Reconciliation of Revenue and Operating Income from Segments to Consolidated (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues	$ 273,282	$ 235,558	$ 796,218	$ 536,265
Depreciation and amortization	(6,933)	(4,523)	(19,879)	(8,527)
Other expense	(44,030)	(29,485)	(124,870)	(47,784)
Income before income taxes	40,292	31,644	106,227	81,942
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues	273,282	235,558	796,218	536,265
Operating income loss before depreciation and amortization	95,264	69,635	264,536	147,416
Depreciation and amortization	(6,933)	(4,523)	(19,879)	(8,527)
Stock-based compensation	(4,009)	(3,983)	(13,560)	(9,163)
Other expense	(44,030)	(29,485)	(124,870)	(47,784)
Income before income taxes	40,292	31,644	106,227	81,942
Operating Segments [Member] | Portfolio Purchasing and Recovery [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues	264,800	230,885	775,476	523,659
Operating income loss before depreciation and amortization	91,470	67,803	256,756	143,961
Operating Segments [Member] | Tax Lien Transfer [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues	8,482	4,673	20,742	12,606
Operating income loss before depreciation and amortization	$ 3,794	$ 1,832	$ 7,780	$ 3,455