Common, Treasury and Preferred Shares (Details) (USD $)	12 Months Ended				9 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended				3 Months Ended			12 Months Ended			12 Months Ended		1 Months Ended			12 Months Ended
	Dec. 31, 2013 Loans	Dec. 31, 2012	Dec. 31, 2011	Jun. 27, 2012	Dec. 31, 2013 $75.0MillionATM [Domain]	Dec. 31, 2013 $75.0MillionATM [Domain]	Sep. 30, 2007 Common Stock	Dec. 31, 2013 Common Stock	Dec. 31, 2012 Common Stock	Dec. 31, 2012 August 2010 At The Market (ATM) Program [Member]	Dec. 31, 2011 August 2010 At The Market (ATM) Program [Member]	Dec. 31, 2008 Preferred Stock [Member]	Dec. 31, 2013 Preferred Stock [Member]	Dec. 31, 2013 Series A Preferred Stock [Member]	Dec. 31, 2013 Class A Cumulative Redeemable Preferred [Member]	Dec. 31, 2013 Series B Preferred Stock [Member]	Dec. 31, 2013 Class B Series I Cumulative Preferred Shares [Member]	Dec. 31, 2013 Class B Series II Cumulative Redeemable Preferred Shares [Member]	Dec. 31, 2013 Noncumulative Preferred Stock [Member]	Dec. 31, 2008 July 2005 and October 06 Stock Repurchase Program [Member]	Jul. 31, 2005 July 2005 and October 06 Stock Repurchase Program [Member]	Dec. 31, 2008 December 2008 Stock Repurchase Program [Member]	Dec. 31, 2013 Restricted Stock [Member]
Class of Stock [Line Items]
Common stock authorized through equity offering program						$ 75,000,000				$ 25,000,000
Stock sold		2,921,667				107,498			6,325,000	681,178	788,676
Net proceeds from sale of stock	116,751,000	98,149,000	13,300,000		1,900,000				87,200,000	11,100,000	13,300,000
Forward Contract Indexed to Issuer's Equity, Base Common Shares								6,500,000
Forward Contract Indexed to Issuer's Equity, Additional Common Shares Option	975,000
Forward Contract Indexed to Issuer's Equity, Additional Common Shares Option Exercised								547,958
Forward Contract Indexed to Issuer's Equity, Shares								7,047,958
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share	$ 17.25
Forward Contract Sale Net Proceeds								115,100,000
Forward Contract Net Settlement Price Per Share	$ 16.33
Number of Mortgages to Repay	5
Extinguishment of Debt, Amount	129,300,000
Price per share in a public offering				$ 14.40
Issuance of common shares		3,403,333
Stock repurchase authorized amount																					50,000,000	25,000,000.0
Stock repurchase remaining authorized repurchase amount																				1,300,000
Stock repurchased, shares								3,825,125					389,500
Stock repurchased, value								$ 41,100,000					$ 7,600,000
Stock repurchased during period, shares							0					0
Restricted shares vested and issued from treasury shares																							466,906
Preferred stock, shares authorized	9,000,000													3,000,000	225,000	3,000,000	400,000	232,000	3,000,000
Preferred stock dividend rate, percentage															9.75%			8.70%