Subsequent Events (Details) (USD $)	3 Months Ended		0 Months Ended	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Apr. 16, 2014 Subsequent Event [Member]	Apr. 09, 2014 10850 Via Frontera San Diego CA [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Dispositions Sales Price				$ 33,100,000
Aggregate dividends, distributions, and dividend equivalents paid to common stockholders and common unitholders	$ 29,561,000	$ 26,956,000	$ 29,800,000