Investments In Direct Financing Lease (Narrative) (Details) (USD $)	0 Months Ended	9 Months Ended		12 Months Ended
	Apr. 02, 2014 properties	Sep. 30, 2014	Sep. 30, 2013 properties	Dec. 31, 2013	Apr. 03, 2014
number of properties sold	4		5
Net Investment in Direct Financing and Sales Type Leases		$ 198,551,000		$ 242,212,000	$ 45,900,000
originalacquisitioncost					41,500,000
Capital Leases, Net Investment in Direct Financing Leases, Initial Direct Costs		1,500,000		1,700,000
Allowance for lease losses		0		0
Payments to Acquire Productive Assets		471,600,000
Proceeds from Sale of Property, Plant, and Equipment	46,100,000
Gain (Loss) on Disposition of Property Plant Equipment		$ 200,000
Minimum [Member]
Length of lease (in years)		18
Maximum [Member]
Length of lease (in years)		21
Imagine Schools [Member]
Number of public charter school properties (in properties)		23		27