Equity (Stock Transactions - Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended	0 Months Ended	1 Months Ended		3 Months Ended	9 Months Ended	1 Months Ended	3 Months Ended	9 Months Ended	1 Months Ended	3 Months Ended	9 Months Ended	1 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 At The Market Equity Offering Program [Member] investment_bank	Sep. 30, 2014 At The Market Equity Offering Program [Member] investment_bank	Nov. 04, 2014 Subsequent Event [Member]	Oct. 31, 2014 Subsequent Event [Member] At The Market Equity Offering Program [Member]	Nov. 04, 2014 Subsequent Event [Member] At The Market Equity Offering Program [Member]	Sep. 30, 2014 Minimum [Member] At The Market Equity Offering Program [Member]	Sep. 30, 2014 Minimum [Member] At The Market Equity Offering Program [Member]	Oct. 31, 2014 Minimum [Member] Subsequent Event [Member] At The Market Equity Offering Program [Member]	Sep. 30, 2014 Maximum [Member] At The Market Equity Offering Program [Member]	Sep. 30, 2014 Maximum [Member] At The Market Equity Offering Program [Member]	Oct. 31, 2014 Maximum [Member] Subsequent Event [Member] At The Market Equity Offering Program [Member]	Sep. 30, 2014 Weighted Average [Member] At The Market Equity Offering Program [Member]	Sep. 30, 2014 Weighted Average [Member] At The Market Equity Offering Program [Member]	Oct. 31, 2014 Weighted Average [Member] Subsequent Event [Member] At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Issuance of common stock (shares)					999,080	2,099,380		58,504
Issuance of common stock (price per share)										$ 24.35	$ 24.35	$ 25.00	$ 25.50	$ 25.84	$ 25.35	$ 24.93	$ 25.05	$ 25.32
Net proceeds from issuance of common stock			$ 52,712	$ 220,045	$ 24,500	$ 51,800		$ 1,500
Number of investment banks in sales agreements					4	4
Shares authorized to be sold under the program					9,000,000	9,000,000
Number of authorized shares remaining under offering program									3,233,516
Dividends per share paid to common stockholders (in dollars per share)			$ 0.90
Dividends per share declared to common stockholders (in dollars per share)	$ 0.30	$ 0.30	$ 0.90	$ 0.90			$ 0.30