Net Interest Income (Expense) (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
Interest income:
Short-term investments	$ 432	$ 11	$ 635	$ 54
Mortgage loans at fair value	4,661	1,903	10,675	4,437
Interest income	5,093	1,914	11,310	4,491
Interest expense:
Assets sold under agreements to repurchase	2,920	1,682	8,251	3,583
Note payable	681	281	2,326	645
Other	555	79	1,109	(2)
Interest expense	4,156	2,042	11,686	4,226
Net interest income (expense)	$ 937	$ (128)	$ (376)	$ 265