Segment Information - Reconciliation of Revenue and Operating Income from Segments to Consolidated (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues	$ 297,757	$ 287,796	$ 290,356	$ 285,663	$ 276,571	$ 273,282	$ 269,195	$ 253,741	$ 1,161,572	$ 1,072,789	$ 773,364
Depreciation and amortization									(33,945)	(27,949)	(13,547)
Stock-based compensation									(22,000)	(17,200)	(12,600)
Other expense									184,321	166,829	77,491
Income from continuing operations before income taxes									60,981	152,615	120,868
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues									1,161,572	1,072,789	773,364
Operating income loss before depreciation and amortization									301,255	364,574	224,555
Operating Segments [Member] | Portfolio Purchasing and Recovery [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues									1,129,967	1,043,429	756,277
Operating income loss before depreciation and amortization									337,422	352,754	219,510
Operating Segments [Member] | Tax Lien Transfer [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues									31,605	29,360	17,087
Operating income loss before depreciation and amortization									(36,167)	11,820	5,045
Segment Reconciling Items [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization									(33,945)	(27,949)	(13,547)
Stock-based compensation									(22,008)	(17,181)	(12,649)
Other expense									$ (184,321)	$ (166,829)	$ (77,491)