11. Fair Value measurements (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Finance Receivables Measured at Fair Value:
Balance at beginning of period	$ 30,319	$ 102,366	$ 59,668	$ 160,253
Payments on finance receivables at fair value	(8,848)	(22,449)	(36,828)	(86,556)
Charge-offs on finance receivables at fair value	(535)	(1,259)	(2,275)	(5,309)
Discount accretion	263	1,870	1,247	7,272
Mark to fair value	18	(3,044)	(595)	1,824
Balance at end of period	21,217	77,484	21,217	77,484
Debt Secured by Finance Receivables Measured at Fair Value:
Balance at beginning of period	21,907	104,662	57,107	166,828
Principal payments on debt at fair value	(5,107)	(26,902)	(41,365)	(97,703)
Premium accretion	379	1,687	2,079	5,552
Mark to fair value	(291)	(2,817)	(933)	1,953
Balance at end of period	16,888	76,630	16,888	76,630
Reduction for principal payments collected and payable	(570)	(7,002)	(570)	(7,002)
Adjusted balance at end of period	$ 16,318	$ 69,628	$ 16,318	$ 69,628