Subsequent Events (Details) (USD $)	3 Months Ended				6 Months Ended						1 Months Ended			3 Months Ended
	Sep. 30, 2013	Jun. 30, 2013 property		Jun. 30, 2012 property	Jun. 30, 2013 property		Jun. 30, 2012 property	Jul. 29, 2013	Aug. 02, 2013 2013 Acquisitons [Member] property sqft	Aug. 02, 2013 Future Portfolio Acquisition [Member] property	Aug. 02, 2013 Property Acquisition [Member] property sqft	Aug. 02, 2013 Future Portfolio Acquisition [Member] tenant state sqft	Jun. 30, 2013 Total Portfolio, As of Document End Date [Member] property sqft	Sep. 30, 2013 Underwriter's Option to Purchase Addtional Notes, Proceeds [Member]	Sep. 30, 2013 Underwriter's Option to Purchase Addtional Notes, Proceeds [Member]
Subsequent Event [Line Items]
Proceeds from issuance of convertible obligations to Series C Convertible Preferred stockholders	$ 300,000,000				$ 445,000,000		$ 0							$ 30,000,000.0	$ 10,000,000
Debt Instrument, Interest Rate, Stated Percentage								3.00%
Number of Real Estate Properties									1,207	121			1,181
Number of Properties Acquired		433	[1]	116	481	[1]	170				26
Square feet of property									19,623,186				19,404,596
Square feet of acquired property											218,590	6,200,000.0
Real Estate Investment, Aggregate Purchase Price									2,964,321,000				2,939,004,000
Real Estate Investment Property, at Cost, Acquisitions											$ 25,317,000	$ 604,100,000.0
Occupancy Rate, Percent												100.00%
Real Estate Tenants, Number												16
Investment Grade Income, Percent												35.40%
Average Remaining Lease Life												13 years 9 months 18 days
Geographical Disclosure, Number of States with Real Estate Properties												30

[1] Excludes 47 properties comprised of $67.5 million of net investments subject to direct financing leases