Investment and Mortgage-Backed Securities, Held to Maturity (Schedule of investment and mortgage-backed securities held to maturity) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2013
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Transferred to Available-for-sale Securities, Unrealized Gain (Loss)	$ 1.4
GNMA Mortgage-Backed Securities
Schedule of Held-to-maturity Securities [Line Items]
Held To Maturity, Amortized Cost	$ 72.0

This item represents the unrealized gain (loss) recognized in other comprehensive income (a separate component of shareholders' equity) as a result of securities categorized as held-to-maturity being transferred to the available-for-sale securities category.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27405-111563

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