Investments (Private Label Mortgage Backed Securities) (Details) (USD $) In Thousands, unless otherwise specified			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 RALI2004-QS4 A7 [Member] Lowest Credit Rating Assigned: Standard & Poor's, BBB+ Rating [Member]	Mar. 31, 2013 MALT2004-6 7A1 [Member] Lowest Credit Rating Assigned: Standard & Poor's, CCC Rating [Member]	Mar. 31, 2013 RALI2005-QS2 A1 [Member] Lowest Credit Rating Assigned: Standard & Poor's, C Rating [Member]	Mar. 31, 2013 RALI2006-QS4 A2 [Member] Lowest Credit Rating Assigned: Standard & Poor's, D Rating [Member]	Mar. 31, 2013 GSR 2006-5F 2A1 [Member] Lowest Credit Rating Assigned: Standard & Poor's, D Rating [Member]	Mar. 31, 2013 RALI2006-QS8 A1 [Member] Lowest Credit Rating Assigned: Standard & Poor's, D Rating [Member]	Mar. 31, 2013 Private-label mortgage-backed securities [Member]	Dec. 31, 2012 Private-label mortgage-backed securities [Member]
Schedule of Investments [Line Items]
Origination Date			Mar. 01, 2004	Jun. 01, 2004	Feb. 01, 2005	Apr. 01, 2006	May 01, 2006	Jul. 28, 2006
Amortized Cost	$ 132,112	$ 130,785	$ 287	$ 517	$ 420	$ 682	$ 132	$ 369	$ 2,407	$ 2,539
Investment securities available for sale, at fair value	134,832	133,328	285	525	433	647	132	377	2,399	2,426
Gross Unrealized Gain (Loss)			(2)	8	13	(35)		8	(8)
Collateral Type			ALT A	ALT A	ALT A	ALT A	Prime	ALT A
Lowest Credit Rating Assigned to Private Label Mortgage Backed Securities			BBB+	CCC	C	D	D	D
Credit Support %			11.92%	12.46%	6.49%
Cumulative OTTI Charges						$ 278	$ 15	$ 197	$ 490