Related Party Arrangements (Details) (USD $)	9 Months Ended			9 Months Ended	1 Months Ended	9 Months Ended		0 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Behringer OP sqft	Aug. 31, 2012 Participating, voting, convertible preferred stock	Sep. 30, 2012 Behringer Advisors and its affiliates	Sep. 30, 2012 Behringer Advisors and its affiliates Maximum	Aug. 31, 2012 Behringer Advisors, LLC	Sep. 30, 2012 Behringer Advisors, LLC	Sep. 30, 2011 Behringer Advisors, LLC	Sep. 30, 2011 Behringer Advisors, LLC Maximum	Sep. 30, 2012 HPT Management	Sep. 30, 2011 HPT Management	Sep. 30, 2012 HPT Management Maximum	Sep. 30, 2012 Services Holdings Participating, voting, convertible preferred stock	Aug. 31, 2012 Services Holdings Participating, voting, convertible preferred stock	Sep. 30, 2012 Behringer Advisors, LLC and HPT Management Services, LLC	Dec. 31, 2011 Behringer Advisors, LLC and HPT Management Services, LLC
Related party arrangements
Gross management and oversight fees earned multiplier to derive buyout consideration												0.8
Period for which management and oversight fees earned are considered to derive buyout consideration												12 months
Shares issued																10,000
Share price (in dollars per share)																$ 1.00
Base for conversion ratio (as a percent)					10.00%
Redemption value of preferred stock															100,000
Redemption price (in dollars per share)															$ 10.00
Fair value of preferred stock	2,700,000
Consideration for use of tangible assets, license under the license agreement and for the other agreements, covenants and obligations								1,500,000
Percentage of acquisition and advisory fees payable by the entity							2.50%
Percentage of expenses reimbursed by the entity							0.50%
Debt financing fees (as a percent)						1.00%
Amount of acquisition fees, advisory fees and reimbursement of expenses earned by related party							2,200,000				100,000
Amount of debt financing fees							700,000				2,700,000
Percentage of annual asset management fees based on aggregate asset value for operating assets									0.60%
Percentage of annual asset management fees based on total contract purchase price plus budgeted improvement costs									0.60%
Percentage of asset management fees payable monthly									0.0005
Property management fees												10,400,000	10,800,000
Asset management fees waived	5,700,000	4,900,000
Increase in fixed fee amount or hourly billing rate on January 1, 2013 (as a percent)								1.50%
Annual increase in fixed fee amount or hourly billing rate in subsequent years (as a percent)								3.00%
Amount of reimbursement of costs and expenses									3,200,000	2,900,000		17,700,000	18,700,000
Property management fees (as a percent)												3.00%
Construction supervision fees (as a percent)														5.00%
Oversight fee (as a percent)												0.50%
Asset management fees									10,500,000	15,100,000
Amount payable to related parties	1,427,000		1,397,000														1,400,000	1,400,000
Office space				14,000
Lease term				66 months
Annual base rent				$ 200,000