Real Estate Investments (Assets and Liabilities Assumed) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 property	Dec. 31, 2012 property	Dec. 31, 2011 property
Real estate investments, at cost:
Land	$ 333,166	$ 74,209	$ 7,196
Buildings, fixtures and improvements	749,127	131,958	46,085
Total tangible assets	1,082,293	206,167	53,281
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets Acquired in Period	21,176	22,911	4,645
Total assets acquired, net	1,103,469	229,078	57,926
Payments to Acquire Interest in Joint Venture	236,965	0	0
Preferred Equity Investment, Cash Paid	30,000	0	0
Mortgage notes payable used to acquire investments in real estate	(60,000)	(79,188)	(32,650)
Other liabilities assumed	(12,206)	(4,760)	0
Non-controlling Interest Retained by Seller	0	(380)	0
Business Acquisition Cost Of Acquired Entity Cash Paid In Period	1,298,228	144,750	25,276
Number of properties purchased	7	7	5
Leases, Acquired-in-Place [Member]
Real estate investments, at cost:
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets Acquired in Period	81,376	18,867	5,194
Above Market Leases [Member]
Real estate investments, at cost:
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets Acquired in Period	10,389	9,194	0
Below Market Lease [Member]
Real estate investments, at cost:
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets Acquired in Period	$ (70,589)	$ (5,150)	$ (549)