Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended		7 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Aug. 09, 2013	Mar. 01, 2013	Jun. 30, 2013 At The Market Stock Sales [Member]	Mar. 31, 2013 At The Market Stock Sales [Member]	Jun. 30, 2013 At The Market Stock Sales [Member]
Targeted or Tracking Stock, Stock [Line Items]
Common Stock Offering, Maximum Aggregate Price				$ 300,000
number of shares sold					6,530,193	1,889,105	8,419,298
Gross Proceeds from sale of common stock					167,034	44,459	211,493
Proceeds from issuances of common stock	209,506	87			165,692	43,904	209,596
proceeds from sale of common stock weighted average price per share					$ 25.58	$ 23.53	$ 25.12
Commission To Sales Agent, Percent				2.00%
Common Stock, Shares, Issued			8,419,298
Common Stock Offering Maximum Aggregate Price Still Available	$ 88,507