Gross Gains and Losses from Investment Sales (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Gains Losses On Investments [Line Items]
Net realized gain on sale of mortgage-backed securities	$ 7,436	$ 2,500
Collateralized Mortgage Backed Securities
Gains Losses On Investments [Line Items]
Gross gains on MBS	7,436	2,500
Gross losses on MBS

Net gain (loss) resulting from the sales of securitized, pay-through debt securities collateralized by real estate mortgage loans (mortgages).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.13(h))

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration