Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended			12 Months Ended
	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 01, 2010	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2012 Leases, Acquired-in-Place [Member]	Dec. 31, 2012 Above Market Leases [Member]	Dec. 31, 2012 One Year [Member] Leases, Acquired-in-Place [Member]	Dec. 31, 2012 One Year [Member] Above Market Leases [Member]	Dec. 31, 2012 Two Years [Member] Leases, Acquired-in-Place [Member]	Dec. 31, 2012 Two Years [Member] Above Market Leases [Member]	Dec. 31, 2012 Three Years [Member] Leases, Acquired-in-Place [Member]	Dec. 31, 2012 Three Years [Member] Above Market Leases [Member]	Dec. 31, 2012 Four Years [Member] Leases, Acquired-in-Place [Member]	Dec. 31, 2012 Four Years [Member] Above Market Leases [Member]	Dec. 31, 2012 Five Years [Member] Leases, Acquired-in-Place [Member]	Dec. 31, 2012 Five Years [Member] Above Market Leases [Member]	Dec. 31, 2012 Occupied [Member] property	Dec. 31, 2011 Occupied [Member] property	Dec. 31, 2012 Real Estate [Member] Vacant [Member] property	Dec. 31, 2011 Real Estate [Member] Vacant [Member] property	Sep. 30, 2012 Contributor [Member] ARC Real Estate Partners, LLC [Member] property
Summary of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Gross			$ 11,044,000				$ 27,140,000
Period of Amortization for Intangible Asset		7 years 2 months 12 days					7 years 4 months 2 days	5 years 0 months 10 days
Acquisition related	0	3,988,000	1,875,000
Deferred Finance Costs, Current, Net		4,700,000	2,500,000
Cash and cash equivalents	0	2,748,000	3,148,000	0
Number of Real Estate Properties																			147	90	1	2
Amortization of intangible lease assets	0	2,047,000	159,000						3,688,000	252,000	3,619,000	252,000	3,336,000	252,000	3,067,000	252,000	2,531,000	122,000
Accumulated Amortization, Finite-Lived Intangible Asset, Acquired-in-Place-Leases		(5,244,000)	(3,197,000)
Cash in excess of FDIC limit		2,200,000	2,700,000
Real Estate Property, Weighted Average Remaining Lease Term					2 years	20 years
Finite-Lived Intangible Asset, Acquired-in-Place Leases, Net of Accumulated Amortization		21,896,000	7,847,000
Finite-Lived Intangible Asset, Off-market Lease, Favorable, Gross		1,264,000	0
Accumulated Amortization, Finite-Lived Intangible Asset, Off-Market Lease, Favorable		(116,000)	0
Off Market Leases, Unfavorable, Net of Accumulated Amortization		1,148,000	0
Finite-Lived Intangible Assets, Net		23,044,000	7,847,000
Deferred Costs, Leasing, Net		200,000	300,000
Deferred Offering Costs		100,000
Number Of Properties Contributed By Affiliate																							63
Maximum Amount of Offering from Universal Shelf Registration Statement		$ 500,000,000