Mortgage Loans Held for Sale at Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Mortgage Loans Held for Sale at Fair Value
Mortgage loans held for sale at fair value	$ 530,248	$ 448,384
Fair value of mortgage loans pledged to secure mortgage loans sold under agreements to repurchase	522,031	438,850
Conforming
Mortgage Loans Held for Sale at Fair Value
Mortgage loans held for sale at fair value	57,651	50,003
Government-insured or guaranteed
Mortgage Loans Held for Sale at Fair Value
Mortgage loans held for sale at fair value	468,412	398,381
Repurchased mortgage loans
Mortgage Loans Held for Sale at Fair Value
Mortgage loans held for sale at fair value	$ 4,185