Fair Value Measurements - Additional Information (Detail) (USD $)							3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2014 Cabot and Marlin Acquisitions [Member]	Dec. 31, 2013 Cabot Acquisition [Member]	Mar. 31, 2014 Cost to collect [Member]	Mar. 31, 2014 Discount rate [Member]	Mar. 31, 2014 United States [Member]	Mar. 31, 2014 United Kingdom [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Increase or decrease of the fair value							$ 32,400,000	$ 35,700,000
Fluctuation in discount rate	1.00%
Estimated market participant cost to collect									50.30%	30.20%
Discount rate									12.00%	19.50%
Carrying value of investment in receivable portfolios	1,904,030,000	1,590,249,000	801,525,000	873,119,000
Convertible senior notes, carrying value	448,500,000	287,500,000
Convertible senior notes, debt discount	57,881,000	42,240,000
Fair value estimate of convertible senior notes incorporates quoted market prices	538,400,000	412,400,000			1,300,000,000	680,700,000
Senior secured notes, carrying value	55,000,000	58,750,000			1,230,401,000	646,855,000
Senior secured notes, debt premium	$ 79,964,000	$ 43,583,000			$ 80,000,000	$ 43,600,000