Schedule of Preferred Shares Outstanding (Details)	Mar. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Number of Shares	7,150,000us-gaap_PreferredStockSharesOutstanding	7,150,000us-gaap_PreferredStockSharesOutstanding
7 1/2% Series H Preferred Shares [Member]
Class of Stock [Line Items]
Number of Shares	2,750,000
6 3/8% Series I Preferred Stock [Member]
Class of Stock [Line Items]
Number of Shares	4,400,000

Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29

-Article 5

Name:	us-gaap_PreferredStockSharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant