Debt (Details) (USD $)	3 Months Ended		12 Months Ended				3 Months Ended	12 Months Ended			3 Months Ended									3 Months Ended			3 Months Ended				3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2010	Dec. 31, 2013	Mar. 31, 2014 Line of Credit [Member]	Mar. 31, 2014 Unsecured Term Loan [Member]	Mar. 31, 2014 6% Convertible Guaranteed Note [Member]	Dec. 31, 2010 6% Convertible Guaranteed Note [Member]	Dec. 31, 2013 6% Convertible Guaranteed Note [Member]	Mar. 31, 2013 6% Convertible Guaranteed Note [Member]	Mar. 31, 2014 Other Debt Obligations [Member]	Mar. 31, 2013 Other Debt Obligations [Member]	Mar. 31, 2014 Minimum [Member]	Dec. 31, 2013 Minimum [Member]	Mar. 31, 2014 Maximum [Member]	Dec. 31, 2013 Maximum [Member]	Jun. 30, 2013 Senior Notes Due 2023 [Member] Senior Notes [Member]	Mar. 31, 2014 Unsecured Revolving Credit Facility, Expiring February 2018 [Member]	Mar. 31, 2014 Unsecured Revolving Credit Facility, Expiring February 2018 [Member] Unsecured Revolving Credit Facility [Member]	Mar. 31, 2014 Unsecured Revolving Credit Facility, Expiring February 2018 [Member] Minimum [Member]	Mar. 31, 2014 Unsecured Revolving Credit Facility, Expiring February 2018 [Member] Maximum [Member]	Mar. 31, 2014 Unsecured Revolving Credit Facility, Expiring January 2019 [Member] Unsecured Term Loan [Member]	Mar. 31, 2014 Unsecured Revolving Credit Facility, Expiring January 2019 [Member] Minimum [Member] Unsecured Term Loan [Member]	Mar. 31, 2014 Unsecured Revolving Credit Facility, Expiring January 2019 [Member] Maximum [Member] Unsecured Term Loan [Member]	Mar. 31, 2014 Term Loan Facility from Key Bank [Member]	Mar. 31, 2014 Term Loan Facility from Key Bank [Member] Unsecured Term Loan [Member]	Mar. 31, 2014 Term Loan Facility from Key Bank [Member] Minimum [Member]	Mar. 31, 2014 Term Loan Facility from Key Bank [Member] Maximum [Member]	Mar. 31, 2014 Convertible Debt [Member]	Mar. 31, 2013 Convertible Debt [Member]	Mar. 31, 2014 Interest Rate Contract [Member]	Mar. 31, 2014 Interest Rate Swap [Member]	Mar. 31, 2014 Discontinued Operations [Member]	Dec. 31, 2013 Discontinued Operations [Member]
Debt Instrument [Line Items]
Mortgages and notes payable	$ 1,145,212,000			$ 1,197,489,000																													$ 1,163,835,000	$ 1,197,489,000
Effective interest rate							8.10%		8.10%				3.60%	3.60%	8.50%	8.50%
Debt, Weighted Average Interest Rate	5.30%			5.30%
Debt Instrument, Face Amount						255,000,000	26,186,000	115,000,000	28,991,000								250,000,000		400,000,000							250,000,000
Debt Instrument, Interest Rate, Stated Percentage							6.00%		6.00%	6.00%							4.25%
Debt Instrument, Percentage of Issuance Price																	99.026%
Debt Instrument, Unamortized Discount (Premium), Net							1,244,000		1,500,000								2,435,000
Debt Instrument, Basis Spread on Variable Rate																				0.95%	1.725%		1.50%	2.25%			1.10%	2.10%
Debt Instrument, Interest Rate at Period End																		1.15%				1.75%			1.35%
Derivative, Average Variable Interest Rate																																1.42%
Line of Credit Facility, Amount Outstanding					42,000,000
Letters of Credit Outstanding, Amount					6,144,000
Line of Credit Facility, Remaining Borrowing Capacity					351,856,000
Derivative, Fixed Interest Rate																															1.09%
Long-term Debt, Gross																															250,000,000
Debt Instrument, Maturity Date								Jan. 31, 2030
Percent Of Notes Required To Be Repurchased At The Option Of The Holders On Set Dates			100.00%
Debt Instrument, Convertible, Conversion Ratio							147.8206
Debt Instrument, Convertible, Conversion Price (dollars per share)							$ 6.76
Amount of debt converted																													2,805,000	42,750,000
Debt Conversion, Converted Instrument, Shares Issued	414,637	6,167,111
Convertible debt cash payments	62,000	2,663,000
Debt Satisfaction Charges	574,000	10,633,000
Extinguishment of Debt, Gain (Loss), Net of Tax											$ 2,730,000	$ 70,000