Supplemental Disclosures of Cash Flow Information (Details) (USD $)	3 Months Ended
	Mar. 31, 2014 item	Mar. 31, 2013
Acquisition of American Realty Capital Trust, Inc.
Loans receivable	$ 48,900,000
Number of acquired properties	5
Cash paid for interest	79,900,000	56,200,000
Interest capitalized to properties under development	95,000	229,000
Cash paid for income taxes	942,000	901,000
Non-cash investing and financing activities
Share-based compensation expense	2,697,000	3,845,000
Loans Assumed	45,900,000	48,200,000
Net discounts recorded on mortgages assumed	2,800,000
Interest rate swap agreement acquired	901,000
Net premiums recorded on mortgages assumed		4,200,000
Real estate acquired in exchange of properties		523,000
Increase in buildings and improvements and accounts payable	7,100,000
Land acquired as a portion of a development property		750,000
ARCT
Acquisition of American Realty Capital Trust, Inc.
Real estate investments and related intangible assets		3,200,000,000
Other assets		19,500,000
Lines of credit payable		317,200,000
Term loan		235,000,000
Mortgage notes payable		539,000,000
Acquired lease intangible liabilities		79,700,000
Other liabilities		29,000,000
Noncontrolling interests		$ 14,000,000