Related Person Transactions (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended			3 Months Ended	1 Months Ended		12 Months Ended	0 Months Ended		1 Months Ended	13 Months Ended	35 Months Ended	1 Months Ended					3 Months Ended	0 Months Ended	1 Months Ended
	Dec. 31, 2014 agreement	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2014	Jan. 31, 2014	Jan. 31, 2012	Dec. 31, 2010	Jul. 01, 2013	Jan. 06, 2014	Dec. 31, 2013	Jan. 31, 2012	Dec. 31, 2014 property	Sep. 30, 2014 item	Jun. 30, 2014 item	Mar. 31, 2014	Jul. 31, 2013 item	Mar. 31, 2012	Dec. 31, 2014 agreement installment property building trustee	May 09, 2014	Aug. 31, 2012 property	Jun. 30, 2013	Feb. 27, 2014	Dec. 31, 2008	Aug. 13, 2013	Apr. 15, 2013 property	Jan. 31, 2013	Dec. 23, 2013
Related Party Transaction [Line Items]
Number of management agreements or leases	11											11						11
Rental income	$ 258,062	$ 251,866	$ 300,354
Capital improvements from leased facilities, funded	230,531	346,320	357,084
Increase (decrease) in minimum annual rent	17,670	27,612	27,813
Proceeds received from the VDOT in connection with the eminent domain taking	6,178
Awards granted (in shares)	92,225	94,125	84,017
Gain on sale of real estate	130		10,602
Accruals for unpaid amount	40,253	38,064								38,064		40,253						40,253
Amount owed for capital expenditure reimbursements	8,658	13,194								13,194		8,658						8,658
Earnings (losses) recognized related to equity investments	94	334	316
Sonesta ES Suites
Related Party Transaction [Line Items]
Gain on sale of real estate				130
Full service hotel in Orlando, FL
Related Party Transaction [Line Items]
Purchase price of terminated transaction																						21,000
TA No. 1
Related Party Transaction [Line Items]
Ground rent paid	5,272
TA No. 1 | Travel center located in Roanoke, VA
Related Party Transaction [Line Items]
Proceeds received from the VDOT in connection with the eminent domain taking					6,178
Travel centers
Related Party Transaction [Line Items]
Ground rent paid	491
Hotels
Related Party Transaction [Line Items]
Number of management agreements or leases	9											9						9
Ground rent paid	225
Hotels | Sonesta agreements
Related Party Transaction [Line Items]
Capital improvements from leased facilities, funded	115,836
Fixed minimum return as a percentage of invested capital	8.00%					8.00%
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%											6.00%						6.00%
Hotels | Sonesta agreements | Forecast
Related Party Transaction [Line Items]
Capital improvements from leased facilities, funded	27,000
Hotels | Minimum
Related Party Transaction [Line Items]
Number of real estate properties leased or managed	1											1						1
Renewal period	20 years
Hotels | Maximum
Related Party Transaction [Line Items]
Number of real estate properties leased or managed	91											91						91
Renewal period	60 years
Travel Centers of America LLC
Related Party Transaction [Line Items]
Percentage of ownership formerly held in subsidiary	100.00%											100.00%						100.00%
Number of common shares owned	3,420,000											3,420,000						3,420,000
Common shares of TA held by company as a percent of total TA shares outstanding	8.90%											8.90%						8.90%
Number of Managing Trustees who are Managing Directors	1											1						1
Number of Independent Trustees who are independent directors	1											1						1
Lessee as percentage of real estate properties	35.00%											35.00%						35.00%
Number of management agreements or leases	2											2						2
Rental income	225,394	219,050	208,560
Amount of percentage rent recognized, net of waived amount	2,896	2,102	1,465
Rent payable deferral permitted																							150,000
Deferred percentage rent revenue	150,000						150,000
Number of months following latest expiration terms between agreements	12 months
Accruals for unpaid rent, excluding any deferred rents	40,253	37,034	34,244							37,034		40,253						40,253
Maximum percentage of any class of equity shares that can be acquired without approval	9.80%											9.80%						9.80%
Travel Centers of America LLC | Forecast
Related Party Transaction [Line Items]
Deferred rent due in December 2022	107,085											107,085						107,085
Deferred rent due in June 2024	42,915											42,915						42,915
Travel Centers of America LLC | TA No. 1
Related Party Transaction [Line Items]
Common shares of TA held by company as a percent of total TA shares outstanding								8.50%
Minimum rents payable	164,964											164,964						164,964
Ground rent paid	5,272
Increase (decrease) in minimum annual rent								537
Adjustments included in rental income necessary to record rent on the straight line basis	1,580	1,783	149
Reimbursement of rent due to third party								545
Travel Centers of America LLC | TA No. 1 | Travel center located in Roanoke, VA
Related Party Transaction [Line Items]
Increase (decrease) in minimum annual rent									525
Percent of proceeds received from settlement with VDOT that reduced the rent receivable from TA																								8.50%
Proceeds received from the VDOT in connection with the eminent domain taking					6,178
Ground lease monthly rent to be paid									40
Travel Centers of America LLC | TA No. 2
Related Party Transaction [Line Items]
Common shares of TA held by company as a percent of total TA shares outstanding		8.50%								8.50%
Minimum rents payable	61,964											61,964						61,964
Increase (decrease) in minimum annual rent										105
Travel Centers of America LLC | Travel centers
Related Party Transaction [Line Items]
Number of properties leased	184											184						184							100
Percentage of fuel revenue over threshold amounts						0.30%					0.30%															0.30%
Rate of increase in minimum annual amount (as a percent)	8.50%											8.50%						8.50%
Rate of increase in minimum annual amount, basis spread (as a percent)	3.50%											3.50%						3.50%
Capital improvements from leased facilities, funded	66,133	83,912	76,754
Increase (decrease) in minimum annual rent	5,621	7,133	6,524
Travel Centers of America LLC | Travel centers | TA No. 1
Related Party Transaction [Line Items]
Number of properties leased	144											144						144
Rental income	54,160										135,139	140,139
Travel Centers of America LLC | Travel centers | TA No. 2
Related Party Transaction [Line Items]
Number of properties leased	40											40						40
Number of renewal options available	2
Term of renewal option	15 years
Percentage of non-fuel revenue over threshold amounts						3.00%					3.00%															3.00%
Annual percentage rent to be waived	2,500
Aggregate annual percentage rent waived	986											986						986
Annual percentage rent waived	603	383
RMR
Related Party Transaction [Line Items]
Number of agreements to provide management and administrative services	2											2						2
Number of properties under property management agreement	1											1						1
Number of Managing Trustees who are Chairmen, majority owners and employees of RMR	1											1						1
Percentage of annual payment of business management fee rate up to $ 250,000 of real estate investments		0.70%	0.70%							0.70%
Amount of real estate investments specified as a base for compensation rate		250	250							250
Percentage of annual payment of business management fee rate above $ 250,000 of real estate investments		0.50%	0.50%							0.50%
Base management fee payable monthly in cash (as a percent)	90.00%											90.00%						90.00%
Base management fee payable monthly in fully-vested shares of common shares (as a percent)	10.00%											10.00%						10.00%
Number of common shares to be issued as a percentage of the total base management fee payable divided by the average daily closing price of common shares	10.00%											10.00%						10.00%
Incentive management fee payable as a percentage of product subject to certain limitations and adjustments	12.00%											12.00%						12.00%
Incentive management fee measurement period																		3 years
Incentive management fee measurement period for 2014																		1 year
Incentive management fee measurement period for 2015																		2 years
Percentage of common shares issued in payment of an incentive management fee vested on the date of issuance	33.30%											33.30%						33.30%
Percentage of common shares issued in payment of an incentive management fee vesting thereafter date of issuance in two equal annual installments	66.60%											66.60%						66.60%
Number of equal annual installments in which specified percentage of common shares issued in payment of an incentive management fee vesting thereafter date of issuance	2											2						2
Incentive fee (as a percent)		15.00%	15.00%							15.00%
Maximum value of the incentive fee payable (in dollars per share)		$ 0.02	$ 0.02
Property management fee (as a percent)	3.00%											3.00%						3.00%
Construction management fees (as a percent)	5.00%											5.00%						5.00%
Business and property management agreement expenses	37,672	41,474	35,657
Common shares issued for services rendered by RMR	119,664														102,536		33,132
Share in cost of providing internal audit function by RMR	281	203	193
Amount due for business and incentive management fees and internal audit services	3,403	6,435	3,210							6,435		3,403						3,403
Awards granted (in shares)	79,725	84,125	74,017
Aggregate value of awards granted during the period	2,272	2,307	1,852
Portion of the awards granted that vested on grant date	20.00%
Portion of the awards granted which will vest on each of the next four anniversaries of the grant date	20.00%
Number of anniversaries of the grant date over which the awards vest	4 years
Number of entities to whom RMR provides management services	4												5	4		5
Premium paid for combined directors' and officers' liability insurance policy														50		624
Liability insurance policy term													2 years
Aggregate coverage of combined directors' and officers' liability insurance policy purchased by the related party													10,000			10,000
Additional liability insurance policy term													1 year
Aggregate additional coverage of combined directors' and officers' liability insurance policy purchased by the related party													20,000			5,000
Aggregate coverage of separate directors' and officers' liability insurance policy purchased																5,000
Non-indemnifiable coverage of combined directors' and officers' liability insurance policy purchased by the related party													5,000
Premium payable for combined directors' and officers' liability insurance policy													624
RMR | Amended Agreement
Related Party Transaction [Line Items]
Percentage of annual payment of business management fee rate up to $ 250,000 of real estate investments																											0.70%
Amount of real estate investments specified as a base for compensation rate																											250,000
Percentage of annual payment of business management fee rate above $ 250,000 of real estate investments																											0.50%
Percentage of annual payment of business management fee rate up to $ 250,000 of Average Market Capitalization																											0.70%
Amount of Average Market Capitalization specified as a base for compensation rate																											250,000
Percentage of annual payment of business management fee rate above $ 250,000 of Average Market Capitalization																											0.50%
Period before which the written notice is required to be given for cancellation of the business management agreement or the property management agreement																			120 days
Period before which the written notice was required to be given for cancellation of the business management agreement or the property management agreement before amendment																			60 days
Number of business days before which the notice is required to be given for termination of property management agreement																			5 days
Termination fee factor																			2.75
Number consecutive months for average fees and expenses																			24 months
Number of months used to calculate property management termination fee																			6 months
Period over which transition services will be provided by the related party after termination of the agreement																			120 days
Termination fee factor property management fee																			12
RMR | Hotels
Related Party Transaction [Line Items]
Agreed upon price for sale of hotel																				5,570
Gain on sale of real estate																				392
Number of properties sold																				2
RMR | Hotels | Limited service hotel in Schaumburg IL
Related Party Transaction [Line Items]
Number of properties sold																				1
Sonesta
Related Party Transaction [Line Items]
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%											20.00%						20.00%
Accruals for unpaid amount		893								893
Due to Related Parties	5,250	6,625	10,822							6,625		5,250						5,250
Sonesta | Sonesta agreements
Related Party Transaction [Line Items]
Business and property management agreement expenses	17,800	10,902	5,990
Procurement and construction supervision fees	3,309	2,976
Sonesta | SNSTA
Related Party Transaction [Line Items]
Mortgage loan prepaid						31,035
Interest rate hedge agreement unwound						2,525					2,525
Amount capitalized						25,000					25,000
Equity funding provided by the acquiree's stockholders to facilitate the merger						12,500					12,500
Sonesta | Hotels
Related Party Transaction [Line Items]
Aggregate purchase price advanced						150,500
Number of real estate properties leased or managed	22											22						22
Management fees (as a percent)	3.00%											3.00%						3.00%
Reservation fee entitled to be received by the related party as a percentage of gross room revenues	1.50%											1.50%						1.50%
System fee for centralized services entitled to be received by the related party as a percentage of gross revenues	1.50%											1.50%						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%											3.00%						3.00%
Renewal period	15 years
Period after which the entity has the right to terminate the management agreements without cause upon payment of a termination fee	3 years
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	3 years
Period considered for calculating the minimum return as percentage of invested capital	4 years
Period prior to termination date during which average fees earned is considered for calculation of termination fees	3 years
Annual rate at which the average fees earned is discounted for calculation of termination fees (as a percent)	8.00%											8.00%						8.00%
Base management fee applicable to limited service hotels (as a percent)	5.00%											5.00%						5.00%
Sonesta | Hotels | Sonesta agreements
Related Party Transaction [Line Items]
Cost allocation for reimbursement or other credit as a percentage of applicable hotel's room revenues								1.00%
Cost allocation for reimbursement or other credit as a percentage of total revenues								1.00%
Reservation transmission expenses reimbursement as a percentage of applicable hotel's room revenues								0.80%
Sonesta | Hotels | Maximum
Related Party Transaction [Line Items]
Number of consecutive renewal terms that the entity has the option to renew the agreement	2
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%											6.00%						6.00%
AIC
Related Party Transaction [Line Items]
Shares purchased																			2,857
Price of shares purchased																			825
Equity method investments, ownership percentage	20.00%											20.00%						20.00%	14.30%
Term of property insurance policy														1 year							1 year
Coverage of property insurance policy														500,000							500,000
Total premium due, including taxes and fees			5,256	11,851										11,851							6,842
Amount funded in equity investee	6,034											6,034						6,034
Equity method investments, carrying value	6,834	5,913	5,629							5,913		6,834						6,834
Earnings (losses) recognized related to equity investments	$ 94	$ 334	$ 316
New Orleans Hotel | Hotels
Related Party Transaction [Line Items]
Annual rent payable calculated as a percent of net profit less capital expenditures	75.00%											75.00%						75.00%