Derivatives (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Purchase Contracts item	Dec. 31, 2011 Purchase Contracts item	Sep. 30, 2012 Purchase Contracts TBA agreements item	Dec. 31, 2011 Purchase Contracts TBA agreements item	Sep. 30, 2012 Purchase Contracts IRLCs item	Dec. 31, 2011 Purchase Contracts IRLCs item	Sep. 30, 2012 Sale Contracts item	Dec. 31, 2011 Sale Contracts item	Sep. 30, 2012 Sale Contracts TBA agreements item	Dec. 31, 2011 Sale Contracts TBA agreements item	Sep. 30, 2012 Sale Contracts Eurodollar futures contracts item	Sep. 30, 2012 Sale Contracts Forward agreements item	Dec. 31, 2011 Sale Contracts Forward agreements item
Derivatives
Number of Contracts					916	709	15	1	901	708	114	28	31	17	80	3	11
Notional					$ 358,587,000	$ 127,816,000	$ 201,579,000	$ 589,000	$ 157,008,000	$ 127,227,000	$ 890,423,000	$ 491,900,000	$ 785,423,000	$ 371,000,000	$ 80,000,000	$ 25,000,000	$ 120,900,000
Fair Value					3,514,000	1,696,000	561,000		2,953,000	1,696,000	(5,098,000)	(1,971,000)	(4,957,000)	(1,183,000)		(141,000)	(788,000)
Total gains/(losses) recorded within Principal transactions	$ (6,300,000)	$ (4,400,000)	$ (12,800,000)	$ (17,400,000)