Subsequent Events (Details) (USD $)	1 Months Ended	3 Months Ended	9 Months Ended		1 Months Ended						1 Months Ended					1 Months Ended
	Mar. 31, 2013	Sep. 30, 2013 sqft properties	Sep. 30, 2013 sqft properties	Sep. 30, 2012	Nov. 07, 2013 Subsequent Event [Member] options	Nov. 07, 2013 New York, New York [Member] Subsequent Event [Member] properties acre	Nov. 07, 2013 Danville, Virginia [Member] Subsequent Event [Member]	Nov. 07, 2013 Term Sheet [Member] Subsequent Event [Member]	Sep. 30, 2013 Tenant Improvement [Member]	Nov. 07, 2013 Tenant Improvement [Member] Schaumburg, Illinios [Member] Subsequent Event [Member]	Nov. 07, 2013 Hospital [Member] Kennewick, Washington [Member] Subsequent Event [Member] sqft	Nov. 07, 2013 Hospital [Member] Percentage of Completion, Initial Rate [Member] Kennewick, Washington [Member] Subsequent Event [Member]	Nov. 07, 2013 Hospital [Member] Percentage of Completion, Substantial Completion [Member] Kennewick, Washington [Member] Subsequent Event [Member]	Nov. 07, 2013 Hospital [Member] Percentage of Completion, After Substantial Completion [Member] Kennewick, Washington [Member] Subsequent Event [Member]	Nov. 07, 2013 High-rise Hotels [Member] New York, New York [Member] Subsequent Event [Member] hotel Room sqft Floor	Nov. 07, 2013 Veterinary Hospitals [Member] Joint Venture [Member] Subsequent Event [Member]	Nov. 07, 2013 Veterinary Hospitals [Member] Joint Venture [Member] Nonrecourse Mortgage [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Line of credit, maximum borrowing capacity											$ 85,000,000
Square Feet		1,442,000	1,442,000								168,000				480,000
Lease Term (Years)						99 years					30 years					20 years
Business acquisition, cash paid											110,000,000
Stated interest rate												6.50%	8.75%	9.00%
Estimated ballon payment											87,549,000
Increase in quarterly dividends, percentage					10.00%
Dividends declared		$ 0.15			$ 0.165
Number of acquired properties						3
Area of property						0.6
Number of floors															103
Number of rooms															1,179
Initial annual rent per lease agreement						14,883
Annual rent per lease state as a percentage of the aggregate purchase price						4.90%
Annual minimum lease increase						2.00%
Annual maximum lease increase						3.00%
Total annual aggregate minimum rent						4,541,141,000
Lease, purchase option, original purchase price plus a specified return, amount of specified return						7.50%
Lease, purchase option, specified floor price						305,000,000
Debt Instrument, Face Amount								213,500,000									18,791,000
Debt Instrument, Interest Rate, Stated Percentage								4.66%								4.01%
Debt Instrument, Term								13 years
Change in credit facility borrowings			(67,000,000)	(93,000,000)	216,000,000
Obligation for tenant improvements									234,000	9,000,000
Common shares issued during period	23,000,000				11,500,000
Stock Issued During Period, Value, New Issues					126,270,000
Capitalization Rate							5.50%									6.90%
Number of renewal options					11
Tenant Renewal Options, Term							5 years
Equity Method Investment, Ownership Percentage																15.00%
Consideration transferred			$ 166,468,000			$ 302,000,000	$ 4,727,000									$ 39,456,000
Number of Real Estate Properties		215	215												3