Per Share Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	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
Earnings Per Share [Abstract]
Number of anti-diluted shares outstanding														156
Numerator:
Income (loss) from continuing operations	$ 3,680	$ 4,625	$ 13,925	$ 1,347	$ (1,975)	[1]	$ (3,074)	[1]	$ (19,458)	[1]	$ (430)	[1]	$ 23,577	$ (24,936)	$ 5,173
Income from continuing operations attributable to noncontrolling interests													(423)	(56)	(52)
Income (loss) from continuing operations attributable to common stockholders/unitholders													23,154	(24,992)	5,121
Income from discontinued operations	382	380	308	37	158	[1]	143	[1]	144	[1]	123	[1]	1,107	568	420
Net income (loss) attributable to common stockholders/unitholders	$ 4,062	$ 4,823	$ 14,025	$ 1,351	$ (1,836)	[1]	$ (2,952)	[1]	$ (19,322)	[1]	$ (315)	[1]	$ 24,261	$ (24,424)	$ 5,541
Denominator:
Weighted average number of shares/units outstanding — basic													228,075	222,713	223,900
Dilutive shares													1,864	0	492
Weighted average number of shares/units outstanding — diluted													229,939	222,713	224,392
Earnings (losses) per common share/unit - basic:
Income (loss) from continuing operations attributable to common stockholders/unitholders (usd per share/unit)	$ 0.02	$ 0.02	$ 0.06	$ 0.01	$ (0.01)	[1]	$ (0.01)	[1]	$ (0.08)	[1]	$ 0.00	[1]	$ 0.10	$ (0.11)	$ 0.02
Discontinued operations (usd per share/unit)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.00	$ 0.00	$ 0.00
Net income (loss) attributable to common stockholders/unitholders (usd per share/unit)	$ 0.02	$ 0.02	$ 0.06	$ 0.01	$ (0.01)	[1]	$ (0.01)	[1]	$ (0.08)	[1]	$ 0.00	[1]	$ 0.10	$ (0.11)	$ 0.02
Earnings (losses) per common share/unit - diluted:
Income (loss) from continuing operations attributable to common stockholders/unitholders (usd per share/unit)	$ 0.02	$ 0.02	$ 0.06	$ 0.01	$ (0.01)	[1]	$ (0.01)	[1]	$ (0.08)	[1]	$ 0.00	[1]	$ 0.10	$ (0.11)	$ 0.02
Discontinued operations (usd per share/unit)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.00	[1]	$ 0.00	$ 0.00	$ 0.00
Net income (loss) attributable to common stockholders/unitholders (usd per share/unit)	$ 0.02	$ 0.02	$ 0.06	$ 0.01	$ (0.01)	[1]	$ (0.01)	[1]	$ (0.08)	[1]	$ 0.00	[1]	$ 0.10	$ (0.11)	$ 0.02

[1] The quarterly amounts differ from the previously reported amounts in our Annual Report on Form 10-K for the year ended December 31, 2012 as a result of discontinued operations of one property classified as held for sale during 2013.