Investments in Real Estate (Details) (USD $)	3 Months Ended
	Mar. 31, 2014 item sqft	Mar. 31, 2013	Dec. 31, 2013
Investments in real estate properties
Leasable square feet	66,800,000
Number of investments in properties that caused any tenant to be 10% of more of total assets	0
Loans Assumed	$ 45,900,000	$ 48,200,000
Increase in net income from change in valuation of purchase price allocation measurement		1,400,000
Contingent consideration associated with acquisition	0	0
Total revenue	221,572,000	175,522,000
Income from continuing operations	54,916,000	33,367,000
Intangible value of the in-place leases acquired	898,393,000		843,616,000
Intangible value of above-market leases acquired	227,940,000		207,641,000
In-place lease, depreciation and amortization to expense	20,100,000	13,000,000
Net (increase) decrease to rental income for capitalized above market and below market leases	2,000,000	1,800,000
Net decrease to rental revenue
2014	(6,152,000)
2015	(8,271,000)
2016	(8,283,000)
2017	(8,387,000)
2018	(8,376,000)
Thereafter	(7,799,000)
Totals	(47,268,000)
Increase to amortization expense
2014	58,966,000
2015	76,791,000
2016	76,385,000
2017	75,164,000
2018	72,635,000
Thereafter	423,659,000
Totals	783,600,000
ARCT
Investments in real estate properties
Real estate acquired		3,200,000,000
Number of properties		515
Number of states in which properties are located		44
Leasable square feet		16,000,000
Leased area (as a percent)		100.00%
Weighted average lease term		12 years 2 months 12 days
Number of properties in the portfolio		69
Number of industries in which tenants operate		28
Acquisition transaction costs		12,000,000
ARCT | Retail properties
Investments in real estate properties
Property type- percentage of properties acquired		54.00%
ARCT | Office properties
Investments in real estate properties
Property type- percentage of properties acquired		13.40%
ARCT | Industrial and distribution properties
Investments in real estate properties
Property type- percentage of properties acquired		32.60%
Inland
Investments in real estate properties
Real estate acquired	274,300,000
Number of properties	56
Leased area (as a percent)	100.00%
Number of properties in the portfolio	84
Maximum
Investments in real estate properties
Investments to any one tenant as a percentage of total assets	10.00%
New properties and properties under development or expansion
Investments in real estate properties
Real estate acquired	656,700,000	128,400,000
Number of properties	337	27
Initial weighted average contractual lease rate of properties acquired (as a percent)	7.00%	7.90%
Number of states in which properties are located	35	16
Leasable square feet	4,500,000	477,000
Leased area (as a percent)	100.00%	100.00%
Weighted average lease term	14 years 2 months 12 days	13 years 9 months 18 days
Number of industries in which tenants operate	15	7
Acquisition transaction costs	454,000	143,000
New properties and properties under development or expansion | Retail properties
Investments in real estate properties
Property type- percentage of properties acquired	87.60%	79.80%
New properties and properties under development or expansion | Office properties
Investments in real estate properties
Property type- percentage of properties acquired	4.60%	15.10%
New properties and properties under development or expansion | Industrial and distribution properties
Investments in real estate properties
Property type- percentage of properties acquired	7.80%	5.10%
Properties under development or expansion
Investments in real estate properties
Investments in properties	13,400,000
Number of properties	13
Initial weighted average contractual lease rate of properties acquired (as a percent)	8.40%
Aggregate acquisitions
Investments in real estate properties
Real estate acquired	656,700,000	3,300,000,000
Discounts/(Premiums) recorded upon assumption of mortgages	2,800,000	(26,800,000)
Land recorded related to acquisition	132,200,000	499,300,000
Buildings and improvements recorded	455,300,000	2,280,000,000
Intangible assets related to leases recorded	74,000,000	581,500,000
Other assets recorded	901,000	9,400,000
Intangible liabilities related to leases and other assumed liabilities recorded	8,500,000	81,100,000
Loans Assumed	45,900,000
Total revenue	7,900,000
Income from continuing operations	3,200,000
Amount of investment allocated by estimate	403,800,000
Amount of investment previously allocated by estimate finalized during the period	120,800,000
Investments in Existing Properties
Investments in real estate properties
Total capitalized costs on existing properties	1,400,000	1,700,000
Re-leasing costs included in capitalized costs on existing properties	192,000	413,000
Building and tenant improvements included in capitalized costs on existing properties	1,200,000	1,300,000
Intangible value of below-market leases acquired	8,500,000
Real estate investments with existing leases
Investments in real estate properties
Real estate acquired	403,800,000	3,200,000,000
Number of properties	90	524
Intangible value of the in-place leases acquired	55,900,000	432,500,000
Intangible value of above-market leases acquired	18,000,000	149,000,000
Intangible value of below-market leases acquired	$ 8,500,000	$ 81,100,000