Equity (Details 2) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Class of Stock [Line Items]
Common stock, shares authorized	280,000,000		280,000,000
Preferred stock, shares authorized	50,000,000		50,000,000
Common stock shares issued in connection with stock options exercised	14,530
Common stock issued through the dividend reinvestment plan (in shares)	576	484
Number of shares of stock grants withheld	48,189	32,887
Stock Issued During Period, Shares, Share-based Compensation, Forfeited	12
Issuance of common stock, net	$ 1,102,000	$ 1,973,000
Continuous Equity Program CEP IV [Member]
Class of Stock [Line Items]
Maximum value of shares of common stock that can be sold (in dollars)	$ 1,000,000,000
Common stock shares issued	0
Maximum [Member] | Continuous Equity Program CEP IV [Member]
Class of Stock [Line Items]
Percentage of compensation received by sales agent	2.00%
Restricted Stock and Restricted Stock Converted From Performance Shares [Member]
Class of Stock [Line Items]
Restricted stock granted	193,171