Subsequent Events (Details) (Declaration of Dividends [Member], USD $)	6 Months Ended	3 Months Ended
Jun. 30, 2013	Jun. 30, 2013 Common Stock [Member]	Jun. 30, 2013 Series J Preferred Stock [Member]	Jun. 30, 2013 Series K Preferred Stock [Member]	Jun. 30, 2013 Series L Preferred Stock [Member]
Subsequent Event [Line Items]
Common stock dividends declared per share		$ 0.17
Preferred stock dividends declared per share			$ 0.414063	$ 0.406250	$ 0.412500
Record date		Aug. 15, 2013	Aug. 15, 2013	Aug. 15, 2013	Aug. 15, 2013
Payment date		Aug. 30, 2013	Aug. 30, 2013	Aug. 30, 2013	Aug. 30, 2013
Declared date	Jul. 31, 2013

Aggregate dividends declared during the period for each share of common stock outstanding.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the declared dividend will be paid, in CCYY-MM-DD format.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

+ Details

Name:	us-gaap_DividendPayableDateToBePaidDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the dividend to be paid was declared, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_DividendsPayableDateDeclaredDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_DividendsPayableDateOfRecordDayMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate dividends declared during the period for each share of preferred stock outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_PreferredStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration