Selected Quarterly Financial Data - Additional information (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Impairment charges		$ 6,300,000		$ 3,600,000	$ 7,700,000	$ 2,900,000	$ 200,000	$ 4,200,000
Loss on extinguishment of debt			29,900,000						29,638,000		1,986,000
Loss on extinguishment of debt, discontinued operations			300,000
Gains on sale of real estate	2,700,000	20,200,000	1,800,000		1,200,000	6,300,000		3,400,000	24,718,000	10,874,000	7,035,000
Lease termination fee income								$ 1,500,000