Equity (Tables)

9 Months Ended

Sep. 30, 2013

Targeted or Tracking Stock, Stock [Line Items]

Schedule of Common Stock Outstanding Roll Forward [Table Text Block]

The following table summarizes issuances of common stock sold through the ATM program since inception through September 30, 2013:

	Number of Shares Settled	Gross Proceeds		Net Proceeds		Weighted-average Sales Price
2013:
First quarter	1,889,105	$	44,459	$	43,904	$	23.53
Second quarter	6,530,193	167,034		165,692		25.58
Third quarter	—	—		—		—
Total	8,419,298	$	211,493	$	209,596	$	25.12