Netting of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets	$ 21,731	$ 4,430
Gross amounts offset in the balance sheet	(19,382)	(1,091)
Net amounts of assets presented in the balance sheet	2,349	3,339
Total
Gross amounts of recognized assets	43,448	28,381
Net amounts of assets presented in the balance sheet	24,066	27,290
Net amount	24,066	27,290
Nomura
Total
Net amounts of assets presented in the balance sheet	1,036
Net amount	1,036
Goldman Sachs
Total
Net amounts of assets presented in the balance sheet	591
Net amount	591
Bank of America, N.A.
Total
Net amounts of assets presented in the balance sheet		1,782
Net amount		1,782
Citibank, N.A.
Total
Net amounts of assets presented in the balance sheet		522
Net amount		522
Bank of NY Mellon
Total
Net amounts of assets presented in the balance sheet		311
Net amount		311
Wells Fargo
Total
Net amounts of assets presented in the balance sheet		18
Net amount		18
Other
Total
Net amounts of assets presented in the balance sheet	722	706
Net amount	722	706
MBS put options
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets		967
Forward contracts | Purchases
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets	21,226	1,645
Forward contracts | Sales
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets	505	1,818
IRLCs
Derivatives not subject to master netting arrangements
Gross amounts of recognized assets	21,717	23,951
Total
Net amounts of assets presented in the balance sheet	21,717	23,951
Net amount	$ 21,717	$ 23,951