Related Person Transactions (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended				1 Months Ended		12 Months Ended			12 Months Ended										1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended			1 Months Ended		12 Months Ended	13 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended			12 Months Ended
	Dec. 31, 2011 Agreement Property	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 SNSTA	Jun. 30, 2011 Hotels Y	Jun. 30, 2010 Hotels	Dec. 31, 2011 Hotels Agreement Property	Dec. 31, 2010 Hotels	Feb. 28, 2012 Hotels	Dec. 31, 2011 Hotels Less than Y	Dec. 31, 2011 Travel centers Property	Dec. 31, 2011 Travel centers TA No. 1 Y	Dec. 31, 2011 RMR Agreement employee trustee D Property Y	Dec. 31, 2010 RMR	Dec. 31, 2009 RMR	Dec. 31, 2011 RMR Restricted shares	Dec. 31, 2010 RMR Restricted shares	Dec. 31, 2009 RMR Restricted shares	Dec. 31, 2011 Affiliate of RMR Hotels Property	May 31, 2011 Travel Centers of America LLC	Dec. 31, 2011 Travel Centers of America LLC trustee	Sep. 30, 2010 Travel Centers of America LLC TA No. 1	Dec. 31, 2011 Travel Centers of America LLC Travel centers month Lease	Dec. 31, 2010 Travel Centers of America LLC Travel centers	Dec. 31, 2009 Travel Centers of America LLC Travel centers	Feb. 28, 2011 Travel Centers of America LLC Travel centers TA No. 1	Jan. 31, 2011 Travel Centers of America LLC Travel centers TA No. 1	Dec. 31, 2011 Travel Centers of America LLC Travel centers TA No. 1 Y	Jan. 31, 2012 Travel Centers of America LLC Travel centers TA No. 1	Dec. 31, 2011 Travel Centers of America LLC Travel centers TA No. 1 Less than	Jan. 31, 2011 Travel Centers of America LLC Travel centers TA No. 2	Dec. 31, 2011 Travel Centers of America LLC Travel centers TA No. 2 Y	Dec. 31, 2011 Travel Centers of America LLC Travel centers TA No. 2 Less than Option	Dec. 31, 2011 Sonesta SNSTA	Dec. 31, 2011 Sonesta Hotels Y	Dec. 31, 2011 Sonesta Hotels Less than Term	Dec. 31, 2011 AIC entity	Dec. 31, 2010 AIC	Dec. 31, 2009 AIC
Related Person Transactions
Number of agreements to provide management services													2
Number of Managing Trustees who are Chairmen, majority owners and an employees of RMR													1
Number of employees													740
Number of properties owned	473						288				185								1
Number of properties leased																												145				40
Percentage of annual compensation rate up to $ 250,000 of real estate investments													0.70%
Amount specified as a base for compensation rate													$ 250,000
Percentage of annual compensation rate above $ 250,000 of real estate investments													0.50%
Incentive fee (as a percent)													15.00%
Incentive fee (in dollars per share)													$ 0.02
Number of office building operated (in properties)													1
Property management fee (as a percent)													3.00%
Construction management fees (as a percent)													5.00%
Aggregate fees earned by RMR													34,493	33,229	32,950
Incentive fee earned by RMR													761
Pro rata share in cost of providing audit function by RMR													240	213	220
Period by which business management agreement and property management agreement get automatically renewed (in years)													1
Period before which the written notice is required to be given for cancellation of business management agreement and the property management agreement (in days)													60
Number of business days before which the notice is required to be given for termination of property management agreement (in days)													5
Awards granted (in shares)																67,300	53,900	52,700
Aggregate value of awards granted during the period																1,628	1,186	1,089
Portion of the awards granted that vested on grant date																0.2
Portion of the awards granted which will vest on each of the next four anniversaries of the grant date																0.2
Number of anniversaries of the grant date over which the awards vest (in years)																4 years
Percentage of ownership formerly held in subsidiary																					100.00%
Number of common shares owned																					2,540,000
Additional number of common shares acquired																				1,000,000	1,540,000
Cost of additional investment	5,690																			5,690
Shares owned as a percentage of total shares outstanding																				8.80%	9.60%
Number of management agreements or leases	8						6																2
Number of real estate properties leased																												145				40
Number of renewal options available																																	2
Number of Managing Trustees who are Managing Directors																					1
Number of Independent Trustees who are Independent Directors																					1
Minimum annual rent payable to the entity							242				446																	140,139	135,139			54,160
Percentage of non-fuel revenue																							3.00%
Percentage of fuel revenue																							0.30%
Annual percentage rent to be waived																							2,500									2,500
Annual funding agreed to be provided																														25,000
Period during which annual funding will be provided (in years)												5
Total funding																						125,000	125,000
Qualified improvements sold to the entity																								7,015	8,466
Rate of increase in minimum annual amount (as a percent)																							8.50%
Rate of increase in minimum annual amount, basis																							benchmark U.S. Treasury interest rate
Rate of increase in minimum annual amount, basis spread (as a percent)																							3.50%
Capital improvements to leased facilities, funded																							69,122
Increase (decrease) in annual lease rent payable																							5,875			5,000	29,983				12,017
Amount by which lessee has the option to defer monthly rent payment per month																							5,000
Interest rate on deferred amount outstanding (as a percent)																							1.00%
Interest on deferred amount outstanding																								14,100
Period following the latest of the expiration of the lease terms during which the entity can require lessee to conduct registered public offering of common shares issued to the entity (in months)																							12
Deferred rent accrued																								60,000	60,000
Aggregate deferred rent payable to the entity																								150,000	90,000
Deferred rent due in December 2022																							107,085
Deferred rent due in June 2024																							42,915
Rental income	304,582	326,771	302,484																				201,505	190,244	172,074
Adjustments included in rental income necessary to record rent on the straight line basis	4,807																						4,789
Accruals for unpaid amount																							16,115	15,725	13,954
Maximum percentage of any class of equity shares that can be acquired without approval																					9.80%
Right to receive cash for each outstanding share of acquiree's common stock (in dollars per share)																																		$ 31.00
Aggregate purchase price advanced				150,500
Mortgage loan prepaid				31,035
Interest rate hedge agreement unwound				2,525
Amount capitalized																																		25,000
Portion of amount capitalized which was represented by cash consideration for shares of Sonesta common stock																																		0.5
Equity funding provided by the acquiree's stockholders to facilitate the merger				12,500
Fixed minimum return as a percentage of invested capital																																			8.00%
Reservation fee entitled to be received by the related party as a percentage of gross room revenues																																			1.50%
System fee for centralized services entitled to be received by the related party as a percentage of gross revenues																																			1.50%
Procurement and construction supervision fee in connection with renovations, entitled to be received by the related party as a percentage of third party costs																																			3.00%
Incentive fee entitled to be received by the related party as a percentage of the hotel's operating profit after reimbursement of certain advances																																			20.00%
Base management fee which the entity expects will be applicable to full service hotels (as a percent)																																			3.00%
Base management fee which the entity expects will be applicable to limited service hotels (as a percent)																																			5.00%
Initial term of the management agreement (in years)																																			25
Number of consecutive renewal terms that the entity has the option to renew the agreement																																				2
Renewal period (in years)										60																									15
Period after which the entity has the right to terminate the management agreements without cause upon payment of a termination fee (in years)																																			3
Minimum return as a percentage of invested capital for the entity to have the right to terminate the management agreements without a termination fee																																				6.00%
Period during which minimum return as a percentage of invested capital must be less than specified percentage for the entity to have the right to terminate the management agreements without a termination fee (in years)																																			3
Period considered for calculating the minimum return as percentage of invested capital (in years)																																			4
Period prior to termination date during which average fees earned is considered for calculation of termination fees (in years)																																			3
Annual rate at which the average fees earned is discounted for calculation of termination fees (as a percent)																																			8.00%
Number of other companies which are shareholders of related party																																					4
Equity method investments, ownership percentage																																					14.29%
Amount invested in equity investee									5,209
Equity method investments, carrying value							5,291	5,077
Earnings (losses) recognized related to equity investments	139	(1)	(134)																																		0	(1)	(134)
Coverage of property insurance						500,000
Period for which property insurance program was extended (in years)					1
Annual premium for property insurance							5,773	4,816
Amount paid to the entity in connection with a shareholder derivative litigation											119
Amount paid to RMR in connection with a shareholder derivative litigation											$ 51